U.S. patent number 11,206,114 [Application Number 16/447,670] was granted by the patent office on 2021-12-21 for sounding reference signals and channel state information reference signals enhancements for coordinated multipoint communications.
This patent grant is currently assigned to QUALCOMM INCORPORATED. The grantee listed for this patent is QUALCOMM Incorporated. Invention is credited to Piyush Gupta, Vinay Joseph, Mostafa Khoshnevisan, Alexandros Manolakos, Farhad Meshkati.
United States Patent |
11,206,114 |
Joseph , et al. |
December 21, 2021 |
Sounding reference signals and channel state information reference
signals enhancements for coordinated multipoint communications
Abstract
In an aspect of the disclosure, a method, a computer-readable
medium, and an apparatus are provided. The apparatus may be a user
equipment (UE). The apparatus may transmit a supported
configuration of the UE for at least one of SRS transmission or
CSI-RS reception for communication with a plurality of TRPs. The
apparatus may receive, in response to transmitting the supported
configuration, configuration information for at least one of the
SRS transmission or the CSI-RS reception, wherein the configuration
information is generated based on the supported configuration. The
apparatus may communicate, with at least a subset of the plurality
of TRPs, using at least one of the SRS transmission or the CSI-RS
reception on resource elements assigned based on the configuration
information. A base station connected to the TRPs may use the
SRS/CSI-RS for cluster management and scheduling or to estimate
downlink channels to determine precoding for downlink
transmissions.
Inventors: |
Joseph; Vinay (San Diego,
CA), Khoshnevisan; Mostafa (San Diego, CA), Meshkati;
Farhad (San Diego, CA), Gupta; Piyush (Bridgewater,
NJ), Manolakos; Alexandros (San Diego, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Assignee: |
QUALCOMM INCORPORATED (San
Diego, CA)
|
Family
ID: |
1000006004683 |
Appl.
No.: |
16/447,670 |
Filed: |
June 20, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200014507 A1 |
Jan 9, 2020 |
|
Foreign Application Priority Data
|
|
|
|
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Jul 9, 2018 [GR] |
|
|
20180100309 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
5/0035 (20130101); H04W 72/0446 (20130101); H04L
5/0048 (20130101); H04W 72/042 (20130101) |
Current International
Class: |
H04L
5/00 (20060101); H04W 72/04 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Nokia et al. "UL SRS design considerations in NR," R1-1708928, May
19, 2017, 3GPP. cited by examiner .
Intel Corporation: "Details for UL Beam Management", 3GPP TSG RAN
WG1 Meeting #88bis, 3GPP Draft; R1-1707354 Details for UL Beam
Management, vol. RAN WG1, No. Hangzhou; May 15-19, 2017, May 14,
2017 (May 14, 2017), pp. 1-8, XP051272566, Retrieved from the
Internet: URL:
http://www.3gpp.org/ftp/Meetings_3GPP_SYNC/RAN1/Docs/ [retrieved on
May 14, 2017], Section 2. cited by applicant .
International Search Report and Written
Opinion--PCT/US2019/039962--ISA/EPO--Oct. 11, 2019. cited by
applicant .
Nokia et al "UL SRS Design Considerations in NR", 3GPP TSG RAN WG1
Meeting #89, 3GPP Draft; R1-1708928, vol. RAN WG1, No. Hangzhou;
May 15-19, 2017, May 6, 2017 (May 6, 2017), 7 Pages, XP051262775,
Retrieved from the Internet: URL:
http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_89/Docs/ [retrieved
on May 6, 2017], Section 2. cited by applicant.
|
Primary Examiner: Lee; Jae Y
Attorney, Agent or Firm: Procopio, Cory, Hargreaves &
Savitch LLP
Claims
What is claimed is:
1. A method of wireless communication by a user equipment (UE),
comprising: transmitting a supported configuration of the UE for
sounding reference signal (SRS) transmission with one or more
transmission reception points (TRPs); receiving configuration
information for the SRS transmission, wherein the configuration
information is based on the supported configuration; and
communicating with the one or more TRPs, using the SRS transmission
on resource elements assigned based on the configuration
information, wherein the supported configuration by the UE of the
SRS transmission comprises information indicating the UE supports
one or more of transmitting the SRS transmission over a first span
of an integer number of resource blocks during a slot, transmitting
the SRS transmission using every resource element over a second
span of one or more resource blocks during the slot, or
transmitting the SRS transmission using one of every N resource
elements over a third span of one or more resource blocks during
the slot, wherein N is greater than 4.
2. The method of claim 1, wherein the supported configuration
comprises an SRS comb density supported by the UE, and wherein
communicating with the one or more TRPs includes transmitting the
SRS transmission on the resource elements, which are assigned based
on the SRS comb density supported by the UE.
3. The method of claim 2, wherein the SRS transmission is based on
a cyclic shift that is based on a number of the resource elements
assigned for the SRS transmission.
4. The method of claim 1, wherein a number of cyclic shifts in a
set of cyclic shifts for a sequence for the SRS transmission is
based on a value of a comb density for the SRS transmission or a
number of the resource elements assigned for the SRS
transmission.
5. The method of claim 1, wherein the configuration information is
received from at least one of the one or more TRPs in one or more
of a radio resource control (RRC) message, a medium access control
(MAC) control element (CE), a non-access stratum (NAS) message, or
a downlink control information (DCI).
6. The method of claim 1, wherein the supported configuration by
the UE of the SRS transmission comprises information indicating the
UE supports transmitting the SRS transmission using one of every N
resource elements over the third span of one or more resource
blocks during the slot, wherein N is greater than 4.
7. The method of claim 1, wherein the supported configuration
comprises the SRS transmission using every resource element over
the second span of the one or more resources blocks during the
slot, and the configuration information received by the UE
comprises information configuring the UE to transmit a first set of
SRS on each resource element over the first span of a first integer
number of resource blocks during the slot.
8. The method of claim 7, wherein communicating with the one or
more TRPs comprises transmitting the first set of SRS on each
resource element over the first span of the first integer number of
resource blocks during a first slot.
9. The method of claim 8, wherein the configuration information
configures the UE to transmit a second set of the SRS on one of
every J resource elements over a fourth span of a second integer
number of resource blocks during the slot using a cyclic shift for
a sequence associated with the second set of the SRS, wherein J is
greater than 1.
10. The method of claim 9, wherein J is greater than four.
11. The method of claim 1, wherein the supported configuration of
the UE is for an SRS transmission with a plurality of TRPs.
12. The method of claim 1, wherein a number of cyclic shifts in a
set of cyclic shifts for a sequence for the SRS transmission is
based on a value of a comb density for the SRS transmission having
N being greater than 4.
13. A method of wireless communication by a user equipment (UE),
comprising: transmitting a supported configuration of the UE for
channel state information reference signal (CSI-RS) reception with
one or more transmission reception points (TRPS), wherein the
supported configuration of the UE comprises a CSI-RS density
supported by the UE and indicates that the UE supports one or more
of receiving the CSI-RS on one of every N resource elements over a
first span of one or more resource blocks during a slot, wherein N
is greater than 24, or receiving the CSI-RS over a second span of K
resource blocks during the slot, wherein K is less than 2;
receiving, in response to transmitting the supported configuration,
configuration information for the CSI-RS reception, wherein the
configuration information is based on the supported configuration;
and communicating with the one or more TRPs, using the CSI-RS
reception on resource elements assigned based on the configuration
information.
14. The method of claim 13, wherein the configuration information
configures the UE to receive the CSI-RS on one of every M resource
elements over a third span of J resource blocks during the slot,
wherein M is greater than or equal to N, and wherein communicating
with the one or more TRPs comprises receiving, from one of the one
or more TRPs, the CSI-RS on one of every said M resource elements
over the third span of J resource blocks during a first slot.
15. The method of claim 13, wherein the supported configuration of
the UE is for the CSI-RS reception with a plurality of TRPs.
16. A method of wireless communication by a user equipment (UE),
comprising: transmitting a supported configuration of the UE for
channel state information reference signal (CSI-RS) reception with
one or more transmission reception points (TRPS), wherein the
supported configuration by the UE of the CSI-RS reception comprises
information indicating the UE supports receiving more than a
threshold number of CSI-RS resources during a slot, wherein the
threshold number of CSI-RS resources during the slot comprises a
threshold number of non-zero power (NZP) CSI-RS resources received
in a component carrier during the slot, wherein the threshold
number of NZP CSI-RS resources is greater than 32; receiving, in
response to transmitting the supported configuration, configuration
information for the CSI-RS reception, wherein the configuration
information is based on the supported configuration; and
communicating with the one or more TRPs, using the CSI-RS reception
on resource elements assigned based on the configuration
information.
17. The method of claim 16, wherein the supported configuration of
the UE is for the CSI-RS reception with a plurality of TRPs.
18. A method of wireless communication by a base station,
comprising: receiving, from a user equipment (UE), a supported
configuration of the UE for sounding reference signals (SRS)
transmission with one or more transmission reception points (TRPs);
generating, by the base station, configuration information for the
SRS transmission by the UE, wherein the configuration information
is based on the supported configuration of the UE; transmitting the
configuration information to the UE; and communicating, through at
least a subset of the one or more TRPs with the UE, including SRS
reception from the UE on resource elements assigned based on the
configuration information, wherein the supported configuration by
the UE of the SRS transmission comprises information indicating the
UE supports one or more of transmitting the SRS transmission over a
first span of an integer number of resource blocks during a slot,
transmitting the SRS transmission using every resource element over
a second span of one or more resource blocks during the slot, or
transmitting the SRS transmission using one of every N resource
elements over a third span of one or more resource blocks during
the slot, wherein N is greater than 4.
19. The method of claim 18, wherein the supported configuration
comprises an SRS comb density supported by the UE, and wherein
communicating with at least the subset of the one or more TRPs
includes receiving the SRS transmission on the resource elements
assigned by the base station based on the SRS comb density
supported by the UE.
20. The method of claim 18, wherein the SRS transmission is based
on a cyclic shift that is based on a number of the resource
elements assigned for the SRS transmission.
21. The method of claim 18, wherein a number of cyclic shifts in a
set of cyclic shifts for a sequence for the SRS transmission is
based on a value of a comb density for the SRS transmission or a
number of the resource elements assigned for the SRS
transmission.
22. The method of claim 18, wherein the configuration information
is generated by the base station and is transmitted to the UE in
one or more of a radio resource control (RRC) message, a medium
access control (MAC) control element (CE), a non-access stratum
(NAS) message, or a downlink control information (DCI).
23. The method of claim 18, wherein the supported configuration by
the UE of the SRS transmission comprises information indicating the
UE supports transmitting the SRS transmission using one of every N
resource elements over the third span of one or more resource
blocks during the slot, wherein N is greater than 4.
24. The method of claim 18, wherein the supported configuration
comprises the SRS transmission using every resource element over
the second span of the one or more resources blocks during the
slot, and the configuration information is generated by the base
station and comprises information configuring the UE to transmit a
first set of SRS on one of every M resource elements over the first
span of the first integer number of resource blocks during the
slot, wherein M is greater than or equal to 1.
25. The method of claim 24, wherein communicating with the UE
comprises receiving from the UE, the first set of the SRS on one of
every said M resource elements over the first span of the first
integer number of resource blocks during a first slot, the method
further comprising: estimating, by the base station, one or more
downlink channels with the UE based on the first set of the SRS for
determining precoding for one or more downlink transmissions; and
transmitting the one or more downlink transmissions to the UE.
26. The method of claim 24, wherein the configuration information
comprises information configuring the UE to transmit a second set
of the SRS on one of every J resource elements over a fourth span
of a second integer number of resource blocks during the slot using
a cyclic shift for a sequence associated with the second set of the
SRS, wherein J is greater than M, and wherein the cyclic shift is
determined in part based on a number of subcarriers in a symbol
used to transmit the second set of SRS, and wherein communicating
with the UE comprises receiving, from the UE, the second set of the
SRS on one of every said J resource elements over the fourth span
of the second integer number of resource blocks during a second
slot using the cyclic shift for the sequence.
27. The method of claim 26, further comprising: obtaining by the
base station a link quality estimate of one or more uplink channels
or one or more downlink channels with the UE based on the first set
of the SRS and the second set of the SRS for a coordinated
multipoint communication (CoMP) with the UE.
28. The method of claim 18, wherein the supported configuration is
for an SRS transmission with a plurality of TRPs.
29. The method of claim 18, wherein a number of cyclic shifts in a
set of cyclic shifts for a sequence for the SRS transmission is
based on a value of a comb density for the SRS transmission having
N being greater than 4.
30. A method of wireless communication by a base station,
comprising: receiving, from a user equipment (UE), a supported
configuration of the UE for channel state information reference
signals (CSI-RS) reception with one or more transmission reception
points (TRPs), wherein the supported configuration by the UE of the
CSI-RS reception comprises information indicating the UE supports
one or more of receiving the CSI-RS on one of every N resource
elements over a first span of one or more resource blocks during a
slot, wherein N is greater than 24, or receiving the CSI-RS over a
second span of K resource blocks during the slot, wherein K is less
than 2; generating, by the base station, configuration information
for the CSI-RS reception by the UE, wherein the configuration
information is based on the supported configuration of the UE;
transmitting the configuration information to the UE; and
communicating, through the one or more TRPs with the UE, including
CSI-RS transmission to the UE on resource elements assigned based
on the configuration information.
31. The method of claim 30, wherein the configuration information
is generated by the base station and comprises information
configuring the UE to receive the CSI-RS on one of every M resource
elements over a third span of J resource blocks during a slot,
wherein M is greater than or equal to N, and wherein communicating
with the UE comprises transmitting the CSI-RS on one of every said
M resource elements over the third span of J resource blocks during
a first slot.
32. The method of claim 30, wherein the supported configuration is
for the CSI-RS reception with a plurality of TRPs.
33. A method of wireless communication by a base station,
comprising: receiving, from a user equipment (UE), a supported
configuration of the UE for channel state information reference
signals (CSI-RS) reception with one or more transmission reception
points (TRPs), wherein the supported configuration by the UE of the
CSI-RS reception comprises information indicating the UE supports
receiving more than a threshold number of CSI-RS resources during a
slot, and wherein the threshold number of CSI-RS resources during
the slot comprises a threshold number of non-zero power (NZP)
CSI-RS resources received in a component carrier during the slot,
wherein the threshold number of NZP CSI-RS resources is greater
than 32; generating, by the base station, configuration information
for the CSI-RS reception by the UE, wherein the configuration
information is based on the supported configuration of the UE;
transmitting the configuration information to the UE; and
communicating, through the one or more TRPs with the UE, including
CSI-RS transmission to the UE on resource elements assigned based
on the configuration information.
34. The method of claim 33, wherein the supported configuration is
for the CSI-RS reception with a plurality of TRPs.
35. An apparatus for wireless communication at a user equipment
(UE), comprising: a memory; and at least one processor coupled to
the memory and configured to: transmit a supported configuration of
the UE for sounding reference signal (SRS) transmission with one or
more transmission reception points (TRPs); receive configuration
information for the SRS transmission, wherein the configuration
information is based on the supported configuration; and
communicate with the one or more TRPs, using the SRS transmission
on resource elements assigned based on the configuration
information, wherein the supported configuration by the UE of the
SRS transmission comprises information indicating the UE supports
one or more of transmitting the SRS transmission over a first span
of an integer number of resource blocks during a slot, transmitting
the SRS transmission using every resource element over a second
span of one or more resource blocks during the slot, or
transmitting the SRS transmission using one of every N resource
elements over a third span of one or more resource blocks during
the slot, wherein N is greater than 4.
36. The apparatus of claim 35, wherein the supported configuration
comprises an SRS comb density supported by the UE, wherein
communicating with the one or more TRPs includes transmitting the
SRS transmission on the resource elements assigned based on the SRS
comb density supported by the UE, wherein the SRS transmission is
based on a cyclic shift that is based on a number of the resource
elements assigned for the SRS transmission, and wherein a number of
cyclic shifts in a set of cyclic shifts for a sequence for the SRS
transmission is based on a value of the SRS comb density for the
SRS transmission or a number of resource elements assigned for the
SRS transmission.
37. The apparatus of claim 35, wherein the supported configuration
comprises an SRS comb density supported by the UE, and wherein
communication with the one or more TRPs includes the SRS
transmission on the resource elements, which are assigned based on
the SRS comb density supported by the UE.
38. The apparatus of claim 35, wherein the supported configuration
by the UE of the SRS transmission comprises information indicating
the UE supports transmitting the SRS transmission using one of
every N resource elements over the third span of one or more
resource blocks during the slot, wherein N is greater than 4.
39. The apparatus of claim 35, wherein the supported configuration
of the UE is for an SRS transmission with a plurality of TRPs.
40. The apparatus of claim 35, wherein a number of cyclic shifts in
a set of cyclic shifts for a sequence for the SRS transmission is
based on a value of a comb density for the SRS transmission having
N being greater than 4.
41. An apparatus for wireless communication at a base station,
comprising: a memory; and at least one processor coupled to the
memory and configured to: receive, from a user equipment (UE), a
supported configuration of the UE for sounding reference signals
(SRS) transmission with one or more transmission reception points
(TRPs); generate, by the base station, configuration information
for the SRS transmission by the UE, wherein the configuration
information is based on the supported configuration of the UE;
transmit the configuration information to the UE; and communicate,
through at least a subset of the one or more TRPs with the UE,
including SRS reception from the UE on resource elements assigned
based on the configuration information, wherein the supported
configuration by the UE of the SRS transmission comprises
information indicating the UE supports one or more of transmitting
the SRS transmission over a first span of an integer number of
resource blocks during a slot, transmitting the SRS transmission
using every resource element over a second span of one or more
resource blocks during the slot, or transmitting the SRS
transmission using one of every N resource elements over a third
span of one or more resource blocks during the slot, wherein N is
greater than 4.
42. The apparatus of claim 41, wherein the supported configuration
comprises an SRS comb density supported by the UE, and wherein
communicating with at least the subset of the one or more TRPs
includes receiving the SRS transmission on the resource elements
assigned by the base station based on the SRS comb density
supported by the UE, wherein the SRS transmission is based on a
cyclic shift that is based on a number of the resource elements
assigned for the SRS transmission, and wherein a number of cyclic
shifts in a set of cyclic shifts for a sequence for the SRS
transmission is based on a value of the SRS comb density or a
number of the resource elements assigned for the SRS
transmission.
43. The apparatus of claim 41, wherein the supported configuration
is for an SRS transmission with a plurality of TRPs.
44. The apparatus of claim 41, wherein a number of cyclic shifts in
a set of cyclic shifts for a sequence for the SRS transmission is
based on a value of a comb density for the SRS transmission having
N being greater than 4.
45. The apparatus of claim 41, wherein the supported configuration
comprises an SRS comb density supported by the UE, and wherein
communication with the UE includes the SRS reception on the
resource elements, which are assigned based on the SRS comb density
supported by the UE.
46. The apparatus of claim 41, wherein the supported configuration
by the UE of the SRS transmission comprises information indicating
the UE supports transmitting the SRS transmission using one of
every N resource elements over the third span of one or more
resource blocks during the slot, wherein N is greater than 4.
47. An apparatus for wireless communication at a user equipment
(UE), comprising: a memory; and at least one processor coupled to
the memory and configured to: transmit a supported configuration of
the UE for channel state information reference signal (CSI-RS)
reception with one or more transmission reception points (TRPs),
wherein the supported configuration of the UE comprises a CSI-RS
density supported by the UE and indicates that the UE supports one
or more of receiving the CSI-RS on one of every N resource elements
over a first span of one or more resource blocks during a slot,
wherein N is greater than 24, or receiving the CSI-RS over a second
span of K resource blocks during the slot, wherein K is less than
2; receive, in response to transmitting the supported
configuration, configuration information for the CSI-RS reception,
wherein the configuration information is based on the supported
configuration; and communicate with the one or more TRPs, using the
CSI-RS reception on resource elements assigned based on the
configuration information.
48. The apparatus of claim 47, wherein the supported configuration
of the UE is for the CSI-RS reception with a plurality of TRPs.
49. An apparatus for wireless communication at a user equipment
(UE), comprising: a memory; and at least one processor coupled to
the memory and configured to: transmit a supported configuration of
the UE for channel state information reference signal (CSI-RS)
reception with one or more transmission reception points (TRPs),
wherein the supported configuration by the UE of the CSI-RS
reception comprises information indicating the UE supports
receiving more than a threshold number of CSI-RS resources during a
slot, wherein the threshold number of CSI-RS resources during the
slot comprises a threshold number of non-zero power (NZP) CSI-RS
resources received in a component carrier during the slot, wherein
the threshold number of NZP CSI-RS resources is greater than 32;
receive, in response to transmitting the supported configuration,
configuration information for the CSI-RS reception, wherein the
configuration information is based on the supported configuration;
and communicate with the one or more TRPs, using the CSI-RS
reception on resource elements assigned based on the configuration
information.
50. The apparatus of claim 49, wherein the supported configuration
of the UE is for the CSI-RS reception with a plurality of TRPs.
51. An apparatus for wireless communication at a base station,
comprising: a memory; and at least one processor coupled to the
memory and configured to: receive, from a user equipment (UE), a
supported configuration of the UE for channel state information
reference signals (CSI-RS) reception with one or more transmission
reception points (TRPs), wherein the supported configuration by the
UE of the CSI-RS reception comprises information indicating the UE
supports one or more of receiving the CSI-RS on one of every N
resource elements over a first span of one or more resource blocks
during a slot, wherein N is greater than 24, or receiving the
CSI-RS over a second span of K resource blocks during the slot,
wherein K is less than 2; generate, by the base station,
configuration information for the CSI-RS reception by the UE,
wherein the configuration information is based on the supported
configuration of the UE; transmit the configuration information to
the UE; and communicate, through the one or more TRPs with the UE,
including CSI-RS transmission to the UE on resource elements
assigned based on the configuration information.
52. The apparatus of claim 51, wherein the supported configuration
is for the CSI-RS reception with a plurality of TRPs.
53. An apparatus for wireless communication at a base station,
comprising: a memory; and at least one processor coupled to the
memory and configured to: receive, from a user equipment (UE), a
supported configuration of the UE for channel state information
reference signals (CSI-RS) reception with one or more transmission
reception points (TRPs), wherein the supported configuration by the
UE of the CSI-RS reception comprises information indicating the UE
supports receiving more than a threshold number of CSI-RS resources
during a slot, and wherein the threshold number of CSI-RS resources
during the slot comprises a threshold number of non-zero power
(NZP) CSI-RS resources received in a component carrier during the
slot, wherein the threshold number of NZP CSI-RS resources is
greater than 32; generate, by the base station, configuration
information for the CSI-RS reception by the UE, wherein the
configuration information is based on the supported configuration
of the UE; transmit the configuration information to the UE; and
communicate, through the one or more TRPs with the UE, including
CSI-RS transmission to the UE on resource elements assigned based
on the configuration information.
54. The apparatus of claim 53, wherein the supported configuration
is for the CSI-RS reception with a plurality of TRPs.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
This application claims the benefit of Greek Application No.
20180100309, entitled "Sounding Reference Signals and Channel State
Information Reference Signals Enhancements for Coordinated
Multipoint Communications" and filed on Jul. 9, 2018, which is
expressly incorporated by reference herein in its entirety.
BACKGROUND
Technical Field
The present disclosure relates generally to communication systems,
and more particularly, to coordinated multipoint (CoMP)
communications.
Introduction
Wireless communication systems are widely deployed to provide
various telecommunication services such as telephony, video, data,
messaging, and broadcasts. Typical wireless communication systems
may employ multiple-access technologies capable of supporting
communication with multiple users by sharing available system
resources. Examples of such multiple-access technologies include
code division multiple access (CDMA) systems, time division
multiple access (TDMA) systems, frequency division multiple access
(FDMA) systems, orthogonal frequency division multiple access
(OFDMA) systems, single-carrier frequency division multiple access
(SC-FDMA) systems, and time division synchronous code division
multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various
telecommunication standards to provide a common protocol that
enables different wireless devices to communicate on a municipal,
national, regional, and even global level. An example
telecommunication standard is 5G New Radio (NR). 5G NR is part of a
continuous mobile broadband evolution promulgated by Third
Generation Partnership Project (3GPP) to meet new requirements
associated with latency, reliability, security, scalability (e.g.,
with Internet of Things (IoT)), and other requirements. Some
aspects of 5G NR may be based on the 4G Long Term Evolution (LTE)
standard. There exists a need for further improvements in 5G NR
technology. These improvements may also be applicable to other
multi-access technologies and the telecommunication standards that
employ these technologies.
SUMMARY
The following presents a simplified summary of one or more aspects
in order to provide a basic understanding of such aspects. This
summary is not an extensive overview of all contemplated aspects,
and is intended to neither identify key or critical elements of all
aspects nor delineate the scope of any or all aspects. Its sole
purpose is to present some concepts of one or more aspects in a
simplified form as a prelude to the more detailed description that
is presented later.
In an aspect of the disclosure, a method, a computer-readable
medium, and an apparatus are provided. In certain configurations,
the apparatus may be a user equipment (UE). The apparatus may
transmit a supported configuration of the UE for at least one of
sounding reference signal (SRS) transmission or channel state
information reference signal (CSI-RS) reception for communication
with a plurality of transmission reception points (TRPs). The
apparatus may receive, in response to transmitting the supported
configuration, configuration information for at least one of the
SRS transmission or the CSI-RS reception, wherein the configuration
information is generated based on the supported configuration. The
apparatus may communicate, with at least a subset of the plurality
of TRPs, using at least one of the SRS transmission or the CSI-RS
reception on resource elements assigned based on the configuration
information.
In certain other configurations, the apparatus may be a base
station. The base station may be associated with one or more TRPs.
The apparatus may receive a supported configuration by the UE of at
least one of a SRS transmission and a CSI-RS reception for
communication with a plurality of TRPs. The base station may
generate configuration information for at least one of the SRS
transmission and the CSI-RS reception by the UE. The configuration
information may be generated based on the UE's supported
configuration. The base station may transmit the generated
configuration information to the UE. The base station may
communicate with the UE through one or more TRPs using at least one
of the SRS transmission and the CSI-RS reception on resource
elements assigned based on the configuration information.
To the accomplishment of the foregoing and related ends, the one or
more aspects comprise the features hereinafter fully described and
particularly pointed out in the claims. The following description
and the annexed drawings set forth in detail certain illustrative
features of the one or more aspects. These features are indicative,
however, of but a few of the various ways in which the principles
of various aspects may be employed, and this description is
intended to include all such aspects and their equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram illustrating an example of a wireless
communications system and an access network.
FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a
first 5G/NR frame, DL channels within a 5G/NR subframe, a second
5G/NR frame, and UL channels within a 5G/NR subframe,
respectively.
FIG. 3 is a diagram illustrating an example of a base station and
user equipment (UE) in an access network.
FIG. 4 is a diagram illustrating an example factory that may deploy
CoMP in accordance with certain aspects of the disclosure.
FIG. 5 illustrates a wireless communication system that may use
joint transmission (JT)-CoMP in accordance with certain aspects of
the disclosure.
FIG. 6 is a call flow diagram illustrating an implementation of
communication between a UE and a TRP of supported configuration
information of the UE, programmed configuration information from
the TRP, and the transmission and reception of SRS and CSI-RS based
on the programmed configuration information in accordance with
certain aspects of the disclosure.
FIG. 7 illustrates a configuration of using every resource element
or subcarrier over a span of two resource blocks in a slot to
transmit SRS resources from a UE to support precoding for downlink
transmissions in accordance with certain aspects of the
disclosure.
FIG. 8 illustrates a configuration of using one of every 36
resource elements or subcarriers over a number of resource blocks
in a slot to transmit SRS resources from a UE to support cluster
management and scheduling in accordance with certain aspects of the
disclosure.
FIG. 9 is a flowchart of a method of wireless communication that
may be implemented by a UE in accordance with certain aspects of
the disclosure.
FIG. 10 is a conceptual data flow diagram illustrating the data
flow between different modules/means/components in an exemplary
apparatus of a UE in accordance with certain aspects of the
disclosure.
FIG. 11 is a diagram illustrating an example of a hardware
implementation for an apparatus of a UE employing a processing
system in accordance with certain aspects of the disclosure.
FIG. 12 is a flowchart of a method of wireless communication that
may be implemented by a base station in accordance with certain
aspects of the disclosure.
FIG. 13 is a conceptual data flow diagram illustrating the data
flow between different modules/means/components in an exemplary
apparatus of a base station in accordance with certain aspects of
the disclosure.
FIG. 14 is a diagram illustrating an example of a hardware
implementation for an apparatus of a base station employing a
processing system in accordance with certain aspects of the
disclosure.
DETAILED DESCRIPTION
The detailed description set forth below in connection with the
appended drawings is intended as a description of various
configurations and is not intended to represent the only
configurations in which the concepts described herein may be
practiced. The detailed description includes specific details for
the purpose of providing a thorough understanding of various
concepts. However, it will be apparent to those skilled in the art
that these concepts may be practiced without these specific
details. In some instances, well known structures and components
are shown in block diagram form in order to avoid obscuring such
concepts.
Several aspects of telecommunication systems will now be presented
with reference to various apparatus and methods. These apparatus
and methods will be described in the following detailed description
and illustrated in the accompanying drawings by various blocks,
components, circuits, processes, algorithms, etc. (collectively
referred to as "elements"). These elements may be implemented using
electronic hardware, computer software, or any combination thereof.
Whether such elements are implemented as hardware or software
depends upon the particular application and design constraints
imposed on the overall system.
By way of example, an element, or any portion of an element, or any
combination of elements may be implemented as a "processing system"
that includes one or more processors. Examples of processors
include microprocessors, microcontrollers, graphics processing
units (GPUs), central processing units (CPUs), application
processors, digital signal processors (DSPs), reduced instruction
set computing (RISC) processors, systems on a chip (SoC), baseband
processors, field programmable gate arrays (FPGAs), programmable
logic devices (PLDs), state machines, gated logic, discrete
hardware circuits, and other suitable hardware configured to
perform the various functionality described throughout this
disclosure. One or more processors in the processing system may
execute software. Software shall be construed broadly to mean
instructions, instruction sets, code, code segments, program code,
programs, subprograms, software components, applications, software
applications, software packages, routines, subroutines, objects,
executables, threads of execution, procedures, functions, etc.,
whether referred to as software, firmware, middleware, microcode,
hardware description language, or otherwise.
Accordingly, in one or more example embodiments, the functions
described may be implemented in hardware, software, or any
combination thereof. If implemented in software, the functions may
be stored on or encoded as one or more instructions or code on a
computer-readable medium. Computer-readable media includes computer
storage media. Storage media may be any available media that can be
accessed by a computer. By way of example, and not limitation, such
computer-readable media can comprise a random-access memory (RAM),
a read-only memory (ROM), an electrically erasable programmable ROM
(EEPROM), optical disk storage, magnetic disk storage, other
magnetic storage devices, combinations of the aforementioned types
of computer-readable media, or any other medium that can be used to
store computer executable code in the form of instructions or data
structures that can be accessed by a computer.
FIG. 1 is a diagram illustrating an example of a wireless
communications system and an access network 100. The wireless
communications system (also referred to as a wireless wide area
network (WWAN)) includes base stations 102, UEs 104, an Evolved
Packet Core (EPC) 160, and another core network 190 (e.g., a 5G
Core (5GC)). The base stations 102 may include macrocells (high
power cellular base station) and/or small cells (low power cellular
base station). The macrocells include base stations. The small
cells include femtocells, picocells, and microcells.
The base stations 102 configured for 4G LTE (collectively referred
to as Evolved Universal Mobile Telecommunications System (UMTS)
Terrestrial Radio Access Network (E-UTRAN)) may interface with the
EPC 160 through backhaul links 132 (e.g., S1 interface). The base
stations 102 configured for 5G NR (collectively referred to as Next
Generation RAN (NG-RAN)) may interface with core network 190
through backhaul links 184. In addition to other functions, the
base stations 102 may perform one or more of the following
functions: transfer of user data, radio channel ciphering and
deciphering, integrity protection, header compression, mobility
control functions (e.g., handover, dual connectivity), inter-cell
interference coordination, connection setup and release, load
balancing, distribution for non-access stratum (NAS) messages, NAS
node selection, synchronization, radio access network (RAN)
sharing, multimedia broadcast multicast service (MBMS), subscriber
and equipment trace, RAN information management (RIM), paging,
positioning, and delivery of warning messages. The base stations
102 may communicate directly or indirectly (e.g., through the EPC
160 or core network 190) with each other over backhaul links 134
(e.g., X2 interface). The backhaul links 134 may be wired or
wireless.
The base stations 102 may wirelessly communicate with the UEs 104.
Each of the base stations 102 may provide communication coverage
for a respective geographic coverage area 110. There may be
overlapping geographic coverage areas 110. For example, the small
cell 102' may have a coverage area 110' that overlaps the coverage
area 110 of one or more macro base stations 102. A network that
includes both small cell and macrocells may be known as a
heterogeneous network. A heterogeneous network may also include
Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a
restricted group known as a closed subscriber group (CSG). The
communication links 120 between the base stations 102 and the UEs
104 may include uplink (UL) (also referred to as reverse link)
transmissions from a UE 104 to a base station 102 and/or downlink
(DL) (also referred to as forward link) transmissions from a base
station 102 to a UE 104. The communication links 120 may use
multiple-input and multiple-output (MIMO) antenna technology,
including spatial multiplexing, beamforming, and/or transmit
diversity. The communication links may be through one or more
carriers. The base stations 102/UEs 104 may use spectrum up to Y
MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier
allocated in a carrier aggregation of up to a total of Yx MHz (x
component carriers) used for transmission in each direction. The
carriers may or may not be adjacent to each other. Allocation of
carriers may be asymmetric with respect to DL and UL (e.g., more or
fewer carriers may be allocated for DL than for UL). The component
carriers may include a primary component carrier and one or more
secondary component carriers. A primary component carrier may be
referred to as a primary cell (PCell) and a secondary component
carrier may be referred to as a secondary cell (SCell).
Certain UEs 104 may communicate with each other using
device-to-device (D2D) communication link 158. The D2D
communication link 158 may use the DL/UL WWAN spectrum. The D2D
communication link 158 may use one or more sidelink channels, such
as a physical sidelink broadcast channel (PSBCH), a physical
sidelink discovery channel (PSDCH), a physical sidelink shared
channel (PSSCH), and a physical sidelink control channel (PSCCH).
D2D communication may be through a variety of wireless D2D
communications systems, such as for example, FlashLinQ, WiMedia,
Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or
NR.
The wireless communications system may further include a Wi-Fi
access point (AP) 150 in communication with Wi-Fi stations (STAs)
152 via communication links 154 in a 5 GHz unlicensed frequency
spectrum. When communicating in an unlicensed frequency spectrum,
the STAs 152/AP 150 may perform a clear channel assessment (CCA)
prior to communicating in order to determine whether the channel is
available.
The small cell 102' may operate in a licensed and/or an unlicensed
frequency spectrum. When operating in an unlicensed frequency
spectrum, the small cell 102' may employ NR and use the same 5 GHz
unlicensed frequency spectrum as used by the Wi-Fi AP 150. The
small cell 102', employing NR in an unlicensed frequency spectrum,
may boost coverage to and/or increase capacity of the access
network.
A base station 102, whether a small cell 102' or a large cell
(e.g., macro base station), may include an eNB, gNodeB (gNB), or
another type of base station. Some base stations, such as gNB 180
may operate in a traditional sub 6 GHz spectrum, in millimeter wave
(mmW) frequencies, and/or near mmW frequencies in communication
with the UE 104. When the gNB 180 operates in mmW or near mmW
frequencies, the gNB 180 may be referred to as an mmW base station.
Extremely high frequency (EHF) is part of the RF in the
electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and
a wavelength between 1 millimeter and 10 millimeters. Radio waves
in the band may be referred to as a millimeter wave. Near mmW may
extend down to a frequency of 3 GHz with a wavelength of 100
millimeters. The super high frequency (SHF) band extends between 3
GHz and 30 GHz, also referred to as centimeter wave. Communications
using the mmW/near mmW radio frequency band (e.g., 3 GHz-300 GHz)
has extremely high path loss and a short range. The mmW base
station 180 may utilize beamforming 182 with the UE 104 to
compensate for the extremely high path loss and short range.
The base station 180 may transmit a beamformed signal to the UE 104
in one or more transmit directions 182'. The UE 104 may receive the
beamformed signal from the base station 180 in one or more receive
directions 182''. The UE 104 may also transmit a beamformed signal
to the base station 180 in one or more transmit directions. The
base station 180 may receive the beamformed signal from the UE 104
in one or more receive directions. The base station 180/UE 104 may
perform beam training to determine the best receive and transmit
directions for each of the base station 180/UE 104. The transmit
and receive directions for the base station 180 may or may not be
the same. The transmit and receive directions for the UE 104 may or
may not be the same.
The EPC 160 may include a Mobility Management Entity (MME) 162,
other MMES 164, a Serving Gateway 166, a Multimedia Broadcast
Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service
Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172.
The MME 162 may be in communication with a Home Subscriber Server
(HSS) 174. The MME 162 is the control node that processes the
signaling between the UEs 104 and the EPC 160. Generally, the MME
162 provides bearer and connection management. All user Internet
protocol (IP) packets are transferred through the Serving Gateway
166, which itself is connected to the PDN Gateway 172. The PDN
Gateway 172 provides UE IP address allocation as well as other
functions. The PDN Gateway 172 and the BM-SC 170 are connected to
the IP Services 176. The IP Services 176 may include the Internet,
an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming
Service, and/or other IP services. The BM-SC 170 may provide
functions for MBMS user service provisioning and delivery. The
BM-SC 170 may serve as an entry point for content provider MBMS
transmission, may be used to authorize and initiate MBMS Bearer
Services within a public land mobile network (PLMN), and may be
used to schedule MBMS transmissions. The MBMS Gateway 168 may be
used to distribute MBMS traffic to the base stations 102 belonging
to a Multicast Broadcast Single Frequency Network (MBSFN) area
broadcasting a particular service, and may be responsible for
session management (start/stop) and for collecting eMBMS related
charging information.
The core network 190 may include a Access and Mobility Management
Function (AMF) 192, other AMFs 193, a Session Management Function
(SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be
in communication with a Unified Data Management (UDM) 196. The AMF
192 is the control node that processes the signaling between the
UEs 104 and the core network 190. Generally, the AMF 192 provides
QoS flow and session management. All user Internet protocol (IP)
packets are transferred through the UPF 195. The UPF 195 provides
UE IP address allocation as well as other functions. The UPF 195 is
connected to the IP Services 197. The IP Services 197 may include
the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS
Streaming Service, and/or other IP services.
The base station may also be referred to as a gNB, Node B, evolved
Node B (eNB), an access point, a base transceiver station, a radio
base station, a radio transceiver, a transceiver function, a basic
service set (BSS), an extended service set (ESS), a transmit
reception point (TRP), or some other suitable terminology. The base
station 102 provides an access point to the EPC 160 or core network
190 for a UE 104. Examples of UEs 104 include a cellular phone, a
smart phone, a session initiation protocol (SIP) phone, a laptop, a
personal digital assistant (PDA), a satellite radio, a global
positioning system, a multimedia device, a video device, a digital
audio player (e.g., MP3 player), a camera, a game console, a
tablet, a smart device, a wearable device, a vehicle, an electric
meter, a gas pump, a large or small kitchen appliance, a healthcare
device, an implant, a sensor/actuator, a display, or any other
similar functioning device. Some of the UEs 104 may be referred to
as IoT devices (e.g., parking meter, gas pump, toaster, vehicles,
heart monitor, etc.). The UE 104 may also be referred to as a
station, a mobile station, a subscriber station, a mobile unit, a
subscriber unit, a wireless unit, a remote unit, a mobile device, a
wireless device, a wireless communications device, a remote device,
a mobile subscriber station, an access terminal, a mobile terminal,
a wireless terminal, a remote terminal, a handset, a user agent, a
mobile client, a client, or some other suitable terminology.
In CoMP, the base station 102/180 may use reference signals, such
as sounding reference signal (SRS) resources transmitted from a UE
104 to the base station 102/180 and channel state information
reference signal (CSI-RS) resources transmitted from the base
station 102/180 to the UE 104, to obtain link quality estimates.
The base station may use the link quality estimates of uplink
channels and downlink channels between the base station 102/180 and
the UE 104 for cluster management and scheduling, such as
identifying the TRPs or other base stations associated with the
base station 102/180 that will be cooperating to transmit to the UE
104. FIG. 1 illustrates an example of multiple TRPs 107 associated
with base station 102/180. As an example, FIG. 1 illustrates a UE
104 receiving CoMP communication 109 from multiple TRPs 107
associated with base station 102/180. The UE may be associated with
factory equipment involved in factory automation, as an
example.
The base station 102/180 may also use the SRS resources received
from the UE 104 to estimate downlink channels to determine
precoding for the downlink channels between the base station
102/180 and the UE 104 when the downlink channels and the uplink
channels are similar, such as in a TDD system. The base station
102/180 may adapt downlink transmissions from the base station
102/180 to the UE 104 by precoding the downlink transmission based
on the SRS resources.
In certain aspects, the UE 104 may comprise a CoMP SRS/CSI-RS
component 199 configured to transmit to the base station 180
supported configuration of at least one of a SRS transmission and a
CSI-RS reception and to receive configuration information from the
base station 180 for at least one of the SRS transmission and the
CSI-RS reception. The UE 104 may transmit SRS resources to the base
station 180 and receive CSI-RS resources from the base station 180
based on resource elements assigned according to the configuration
information, e.g., as described below in connection with any of
FIGS. 2A-12. Similarly, the base station 180 may comprise a CoMP
SRS/CSI-RS component 198 configured to receive configuration
information from the UE 104 for at least one of the SRS
transmission and the CSI-RS reception, and to transmit
configuration information to the UE 104 for at least one of the SRS
transmission and the CSI-RS reception by the UE 104. The base
station 180 may receive SRS resources from the UE 104 and transmit
CSI-RS resources to the UE 104 based on resource elements assigned
according to the configuration information, e.g., as described
below in connection with any of FIGS. 2A-12. Although the following
description may be focused on 5G NR, the concepts described herein
may be applicable to other similar areas, such as LTE, LTE-A, CDMA,
GSM, and other wireless technologies.
FIG. 2A is a diagram 200 illustrating an example of a first
subframe within a 5G/NR frame structure. FIG. 2B is a diagram 230
illustrating an example of DL channels within a 5G/NR subframe.
FIG. 2C is a diagram 250 illustrating an example of a second
subframe within a 5G/NR frame structure. FIG. 2D is a diagram 280
illustrating an example of UL channels within a 5G/NR subframe. The
5G/NR frame structure may be FDD in which for a particular set of
subcarriers (carrier system bandwidth), subframes within the set of
subcarriers are dedicated for either DL or UL, or may be TDD in
which for a particular set of subcarriers (carrier system
bandwidth), subframes within the set of subcarriers are dedicated
for both DL and UL. In the examples provided by FIGS. 2A, 2C, the
5G/NR frame structure is assumed to be TDD, with subframe 4 being
configured with slot format 28 (with mostly DL), where D is DL, U
is UL, and X is flexible for use between DL/UL, and subframe 3
being configured with slot format 34 (with mostly UL). While
subframes 3, 4 are shown with slot formats 34, 28, respectively,
any particular subframe may be configured with any of the various
available slot formats 0-61. Slot formats 0, 1 are all DL, UL,
respectively. Other slot formats 2-61 include a mix of DL, UL, and
flexible symbols. UEs are configured with the slot format
(dynamically through DL control information (DCI), or
semi-statically/statically through radio resource control (RRC)
signaling) through a received slot format indicator (SFI). Note
that the description infra applies also to a 5G/NR frame structure
that is TDD.
Other wireless communication technologies may have a different
frame structure and/or different channels. A frame (10 ms) may be
divided into 10 equally sized subframes (1 ms). Each subframe may
include one or more time slots. Subframes may also include
mini-slots, which may include 7, 4, or 2 symbols. Each slot may
include 7 or 14 symbols, depending on the slot configuration. For
slot configuration 0, each slot may include 14 symbols, and for
slot configuration 1, each slot may include 7 symbols. The symbols
on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols
on UL may be CP-OFDM symbols (for high throughput scenarios) or
discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols
(also referred to as single carrier frequency-division multiple
access (SC-FDMA) symbols) (for power limited scenarios; limited to
a single stream transmission). The number of slots within a
subframe is based on the slot configuration and the numerology. For
slot configuration 0, different numerologies .mu. 0 to 5 allow for
1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot
configuration 1, different numerologies 0 to 2 allow for 2, 4, and
8 slots, respectively, per subframe. Accordingly, for slot
configuration 0 and numerology .mu., there are 14 symbols/slot and
2.sup..mu. slots/subframe. The subcarrier spacing and symbol
length/duration are a function of the numerology. The subcarrier
spacing may be equal to 2.sup..mu.*15 kHz, where .mu. is the
numerology 0 to 5. As such, the numerology .mu.=0 has a subcarrier
spacing of 15 kHz and the numerology .mu.=5 has a subcarrier
spacing of 480 kHz. The symbol length/duration is inversely related
to the subcarrier spacing. FIGS. 2A-2D provide an example of slot
configuration 0 with 14 symbols per slot and numerology .mu.=0 with
1 slot per subframe. The subcarrier spacing is 15 kHz and symbol
duration is approximately 66.7 .mu.s.
A resource grid may be used to represent the frame structure. Each
time slot includes a resource block (RB) (also referred to as
physical RBs (PRBs)) that extends 12 consecutive subcarriers. The
resource grid is divided into multiple resource elements (REs). The
number of bits carried by each RE depends on the modulation
scheme.
As illustrated in FIG. 2A, some of the REs carry reference (pilot)
signals (RS) for the UE. The RS may include demodulation RS (DM-RS)
(indicated as R.sub.x for one particular configuration, where 100x
is the port number, but other DM-RS configurations are possible)
and channel state information reference signals (CSI-RS) for
channel estimation at the UE. The RS may also include beam
measurement RS (BRS), beam refinement RS (BRRS), and phase tracking
RS (PT-RS).
FIG. 2B illustrates an example of various DL channels within a
subframe of a frame. The physical downlink control channel (PDCCH)
carries DCI within one or more control channel elements (CCEs),
each CCE including nine RE groups (REGs), each REG including four
consecutive REs in an OFDM symbol. A primary synchronization signal
(PSS) may be within symbol 2 of particular subframes of a frame.
The PSS is used by a UE 104 to determine subframe/symbol timing and
a physical layer identity. A secondary synchronization signal (SSS)
may be within symbol 4 of particular subframes of a frame. The SSS
is used by a UE to determine a physical layer cell identity group
number and radio frame timing. Based on the physical layer identity
and the physical layer cell identity group number, the UE can
determine a physical cell identifier (PCI). Based on the PCI, the
UE can determine the locations of the aforementioned DM-RS. The
physical broadcast channel (PBCH), which carries a master
information block (MIB), may be logically grouped with the PSS and
SSS to form a synchronization signal (SS)/PBCH block. The MIB
provides a number of RBs in the system bandwidth and a system frame
number (SFN). The physical downlink shared channel (PDSCH) carries
user data, broadcast system information not transmitted through the
PBCH such as system information blocks (SIBs), and paging
messages.
As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated
as R for one particular configuration, but other DM-RS
configurations are possible) for channel estimation at the base
station. The UE may transmit DM-RS for the physical uplink control
channel (PUCCH) and DM-RS for the physical uplink shared channel
(PUSCH). The PUSCH DM-RS may be transmitted in the first one or two
symbols of the PUSCH. The PUCCH DM-RS may be transmitted in
different configurations depending on whether short or long PUCCHs
are transmitted and depending on the particular PUCCH format used.
Although not shown, the UE may transmit sounding reference signals
(SRS). The SRS may be used by a base station for channel quality
estimation to enable frequency-dependent scheduling on the UL.
FIG. 2D illustrates an example of various UL channels within a
subframe of a frame. The PUCCH may be located as indicated in one
configuration. The PUCCH carries uplink control information (UCI),
such as scheduling requests, a channel quality indicator (CQI), a
precoding matrix indicator (PMI), a rank indicator (RI), and HARQ
ACK/NACK feedback. The PUSCH carries data, and may additionally be
used to carry a buffer status report (BSR), a power headroom report
(PHR), and/or UCI.
FIG. 3 is a block diagram of a base station 310 in communication
with a UE 350 in an access network. In the DL, IP packets from the
5GC 160 may be provided to a controller/processor 375. The
controller/processor 375 implements layer 3 and layer 2
functionality. Layer 3 includes a radio resource control (RRC)
layer, and layer 2 includes a packet data convergence protocol
(PDCP) layer, a radio link control (RLC) layer, and a medium access
control (MAC) layer. The controller/processor 375 provides RRC
layer functionality associated with broadcasting of system
information (e.g., MIB, SIBs), RRC connection control (e.g., RRC
connection paging, RRC connection establishment, RRC connection
modification, and RRC connection release), inter radio access
technology (RAT) mobility, and measurement configuration for UE
measurement reporting; PDCP layer functionality associated with
header compression/decompression, security (ciphering, deciphering,
integrity protection, integrity verification), and handover support
functions; RLC layer functionality associated with the transfer of
upper layer packet data units (PDUs), error correction through ARQ,
concatenation, segmentation, and reassembly of RLC service data
units (SDUs), re-segmentation of RLC data PDUs, and reordering of
RLC data PDUs; and MAC layer functionality associated with mapping
between logical channels and transport channels, multiplexing of
MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs
from TBs, scheduling information reporting, error correction
through HARQ, priority handling, and logical channel
prioritization.
The transmit (TX) processor 316 and the receive (RX) processor 370
implement layer 1 functionality associated with various signal
processing functions. Layer 1, which includes a physical (PHY)
layer, may include error detection on the transport channels,
forward error correction (FEC) coding/decoding of the transport
channels, interleaving, rate matching, mapping onto physical
channels, modulation/demodulation of physical channels, and MIMO
antenna processing. The TX processor 316 handles mapping to signal
constellations based on various modulation schemes (e.g., binary
phase-shift keying (BPSK), quadrature phase-shift keying (QPSK),
M-phase-shift keying (M-PSK), M-quadrature amplitude modulation
(M-QAM)). The coded and modulated symbols may then be split into
parallel streams. Each stream may then be mapped to an OFDM
subcarrier, multiplexed with a reference signal (e.g., pilot) in
the time and/or frequency domain, and then combined together using
an Inverse Fast Fourier Transform (IFFT) to produce a physical
channel carrying a time domain OFDM symbol stream. The OFDM stream
is spatially precoded to produce multiple spatial streams. Channel
estimates from a channel estimator 374 may be used to determine the
coding and modulation scheme, as well as for spatial processing.
The channel estimate may be derived from a reference signal and/or
channel condition feedback transmitted by the UE 350. Each spatial
stream may then be provided to a different antenna 320 via a
separate transmitter 318TX. Each transmitter 318TX may modulate an
RF carrier with a respective spatial stream for transmission.
At the UE 350, each receiver 354RX receives a signal through its
respective antenna 352. Each receiver 354RX recovers information
modulated onto an RF carrier and provides the information to the
receive (RX) processor 356. The TX processor 368 and the RX
processor 356 implement layer 1 functionality associated with
various signal processing functions. The RX processor 356 may
perform spatial processing on the information to recover any
spatial streams destined for the UE 350. If multiple spatial
streams are destined for the UE 350, they may be combined by the RX
processor 356 into a single OFDM symbol stream. The RX processor
356 then converts the OFDM symbol stream from the time-domain to
the frequency domain using a Fast Fourier Transform (FFT). The
frequency domain signal comprises a separate OFDM symbol stream for
each subcarrier of the OFDM signal. The symbols on each subcarrier,
and the reference signal, are recovered and demodulated by
determining the most likely signal constellation points transmitted
by the base station 310. These soft decisions may be based on
channel estimates computed by the channel estimator 358. The soft
decisions are then decoded and deinterleaved to recover the data
and control signals that were originally transmitted by the base
station 310 on the physical channel. The data and control signals
are then provided to the controller/processor 359, which implements
layer 3 and layer 2 functionality.
The controller/processor 359 can be associated with a memory 360
that stores program codes and data. The memory 360 may be referred
to as a computer-readable medium. In the UL, the
controller/processor 359 provides demultiplexing between transport
and logical channels, packet reassembly, deciphering, header
decompression, and control signal processing to recover IP packets
from the 5GC 160. The controller/processor 359 is also responsible
for error detection using an ACK and/or NACK protocol to support
HARQ operations.
Similar to the functionality described in connection with the DL
transmission by the base station 310, the controller/processor 359
provides RRC layer functionality associated with system information
(e.g., MIB, SIBs) acquisition, RRC connections, and measurement
reporting; PDCP layer functionality associated with header
compression/decompression, and security (ciphering, deciphering,
integrity protection, integrity verification); RLC layer
functionality associated with the transfer of upper layer PDUs,
error correction through ARQ, concatenation, segmentation, and
reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and
reordering of RLC data PDUs; and MAC layer functionality associated
with mapping between logical channels and transport channels,
multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from
TBs, scheduling information reporting, error correction through
HARQ, priority handling, and logical channel prioritization.
Channel estimates derived by a channel estimator 358 from a
reference signal or feedback transmitted by the base station 310
may be used by the TX processor 368 to select the appropriate
coding and modulation schemes, and to facilitate spatial
processing. The spatial streams generated by the TX processor 368
may be provided to different antenna 352 via separate transmitters
354TX. Each transmitter 354TX may modulate an RF carrier with a
respective spatial stream for transmission.
The UL transmission is processed at the base station 310 in a
manner similar to that described in connection with the receiver
function at the UE 350. Each receiver 318RX receives a signal
through its respective antenna 320. Each receiver 318RX recovers
information modulated onto an RF carrier and provides the
information to a RX processor 370.
The controller/processor 375 can be associated with a memory 376
that stores program codes and data. The memory 376 may be referred
to as a computer-readable medium. In the UL, the
controller/processor 375 provides demultiplexing between transport
and logical channels, packet reassembly, deciphering, header
decompression, control signal processing to recover IP packets from
the UE 350. IP packets from the controller/processor 375 may be
provided to the 5GC 160. The controller/processor 375 is also
responsible for error detection using an ACK and/or NACK protocol
to support HARQ operations.
At least one of the TX processor 368, the RX processor 356, and the
controller/processor 359 may be configured to perform aspects in
connection with 199 of FIG. 1.
At least one of the TX processor 316, the RX processor 370, and the
controller/processor 375 may be configured to perform aspects in
connection with 198 of FIG. 1.
A base station may use CoMP techniques to communicate between
multiple TRPs associated with a base station and one or more UE.
CoMP techniques may include a coherent joint transmission
technique, a non-coherent joint transmission technique, and/or a
muting technique to improve spatial diversity with a UE. As an
example, CoMP may be employed in FA. The base station may use
spatial diversity techniques among the TRPs when communicating with
a UE to realize ultra-reliability and low latency communication
(URLLC) (e.g., less than 1 ms latency and 10.sup.-6 reliability).
FIG. 4 is a diagram illustrating an example factory environment 400
that may deploy CoMP in accordance with certain aspects of the
disclosure. The factory environment 400 may include, e.g., at least
one sensor/actuator (S/A) 402, at least one programmable logic
controller (PLC) 404, at least one human machine interface (HMI)
406, and at least one management system 408. The SA 402, the PLC
404, the HMI 406, and/or the management system 408 may correspond
to UEs, e.g., UE 104, 350, that receive wireless communication from
a base station, e.g., 102, 180, 310.
In certain implementations, an S/A 402 may include one or more
device components, e.g., such as a rotary motor, linear servo,
and/or position sensor, just to name a few. An S/A 402 may receive
one or more commands (e.g., instructing motion) from at least one
PLC 404, and the S/A 402 may send sensor information (e.g., related
to the motion, position, acceleration of the device or a component
of the device). Multiple PLCs 404 may coordinate with one another
in order to assure the correct instructions are sent to an S/A 402,
and/or to act as a relay between an HMI 406 and an S/A 402.
An HMI 406 may include, e.g., a tablet device, a handheld device, a
wireless device, a panel device, a wearable device, a virtual
reality (VR) device, and/or an augmented reality (AR) device, just
to name a few. An HMI 406 may control an S/A 402. For example, a
user may input instructions into the HMI 406 such as "start" or
"stop," in order to control the motion and/or actions of an SA 402.
In another example, a user may input instructions into the HMI such
as "change mode from `widget 1` to `widget 2.`" Instructions input
into an HMI 406 may be sent to a PLC 404, and the PLC 404 may
configure the instructions (e.g., using custom hardware) so that
the instructions may be understood by an S/A 402.
The management system 408 may include, e.g., one or more of an
industrial personal computer (PC), controller programming,
software, security management, and/or provide long term key
performance indicator (KPI) (e.g., a value that demonstrates how
effectively the example factory environment 400 is achieving key
business objectives). The management system 408 may receive
information related to KPI from one or more HMIs 406. The
management system 408 may send instructions to one or more of the
HMI(s) 406, PLC(s) 404, and/or S/A(s) 402.
The example factory environment 400 may include, e.g., multiple
production cells (e.g., 2, 10, 100, 1000, 10000, etc.), and each
production cell may have dimensions of, e.g., 10 m.times.10
m.times.3 m. Each production cell may include multiple S/As 402. An
example production cell may include, e.g., 1-50 S/As 402 or more
than 50 S/As 402.
Communications between devices in the example factory environment
400 may be effected, e.g., using one or more base stations, nodes,
and/or TRPs (e.g., TRPs 107) located within a production cell. For
communications relating to factory automation, one objective may be
to meet latency and/or reliability target threshold(s) in the
presence of signal fading, shadowing, and/or other scenarios that
may occur in a factory environment in which moving parts and/or
reflective surfaces may obstruct the line of sight between a
sending device (e.g., TRP, UE, PLC, S/A, etc.) and a receiving
device (e.g., TRP, UE, PLC, S/A, etc.).
To meet certain latency and/or reliability target thresholds such
as an ultra-reliability and low latency configuration (URLLC)
(e.g., less than 1 ms latency and 10.sup.-6 reliability) within a
factory setting, a wireless communication system may exploit
spatial diversity. Spatial diversity may be achieved using multiple
TRPs (e.g., TRPs 107) and/or base stations that communicate with
the UE. The TRPs may employ concurrent joint transmission (JT)-CoMP
communications to a UE, non-coherent joint transmission
communications to a UE, or a muting technique where one or more
TRPs are muted and others are transmitting in resources assigned
for communications with a UE.
FIG. 5 illustrates a wireless communication network 500 that may
use CoMP in accordance with certain aspects of the disclosure. The
wireless communication network 500 may be used in, e.g., the
example factory environment 400 described above in connection with
FIG. 4. The wireless communication network 500 may include a first
TRP 502a located in a first cell 501a, a second TRP 502b located in
a second cell 501b, a UE 504 located at a cell edge of the first
cell 501a and the second cell 501b, and a moveable device 506 that
may be used in an automated process. The first TRP 502a and second
TRP 502b may each correspond to, e.g., a base station, e.g., base
station 102, 180, 310. The first TRP 502a and the second TRP 502b
may be connected to a central unit (CU) that may connect to other
TRPs. In one aspect, the CU may be part of a base station, e.g.,
base station 102, 180, 310. In one aspect, the base station may
include one or more of a CU, one or more distributed units, and
multiple TRPs. The UE 504 may correspond to, e.g., UE 104, 350. The
UE 504 may also correspond to any of the S/A 402, the PLC 404, the
HMI 406, or the management system 408 in FIG. 4. Although two TRPs
502a, 502b are illustrated in FIG. 5, the wireless communication
system 500 may include more than two TRPs 502a, 502b that may be
used as a CoMP cluster for sending CoMP communications to the UE
504.
To meet requirements for URLLC within a factory environment, the
wireless communication network 500 may perform CoMP by sending
concurrent downlink transmissions 503a, 503b from multiple TRPs
502a, 502b (e.g., a CoMP cluster) to the UE 504. However, the
performance gains achieved using CoMP may be sensitive to channel
estimation errors that may arise when a moveable device 506
obstructs the direction in which a downlink transmission 503a is
sent, and/or when the UE 504 moves throughout the network.
A CU or a base station connected to the CoMP cluster of TRPs may
identify which TRPs may cooperate to transmit to the UE 504 as part
of cluster management and scheduling. The base station may use
reference signals, such as SRS transmitted by UE 504 and received
by TRPs 502a, 502b, and CSI-RS transmitted by TRPs 502a, 502b to UE
504, to obtain link quality estimates of uplink channels and
downlink channels between TRPs 502a, 502b and UE 504. For example,
the base station may configure the UE to transmit the SRS on
resource elements in a slot. The UE may transmit the SRS on the
configured resource elements and the base station may measure the
received SRS. The base station may use the SRS measurements to
generate an uplink channel estimate and downlink channel estimates
for cluster management and scheduling. The base station may also
use the downlink channel estimates to determine precoding to adapt
downlink transmissions from the TRPs 502a and 502b to the UE 504.
Aspects presented herein improve the allocations and use of SRS
resources and CSI-RS for cluster management and scheduling and/or
for precoding in CoMP. Aspects help to improve the efficient use of
wireless resources and reduction in power consumption while meeting
the unique needs of CoMP, e.g., including cluster management,
scheduling and/or precoding.
FIG. 6 is a call flow diagram 600 illustrating example aspects of
communication between a UE 602 and a TRP 604. The communication may
include supported configuration information of the UE, programmed
configuration information from the TRP, and the transmission and
reception of SRS and CSI-RS based on the programmed configuration
information in accordance with certain aspects of the disclosure.
The TRP 604 may be part of a CoMP cluster that may connect to a
base station, e.g., base station 102, 180, 310.
In 606, the UE 602 may transmit its supported configuration for
uplink SRS transmission to the TRP 604 and/or its supported
configuration for downlink CSI-RS reception from the TRP 604. As
mentioned, the TRP 604 or the base station connected to the TRP 604
may measure the SRS resources transmitted from the UE 602 to
estimate the downlink channel between the TRP 604 and the UE 602 to
determine precoding to be applied to downlink transmission when the
downlink channels and the uplink channels are similar, such as in a
time domain duplex (TDD) system. The UE 602 may transmit the SRS on
resource elements in one or more resource blocks in a slot (e.g.,
in the last symbol of a subframe).
SRS may be transmitted up to a maximum density of one of every 2
resource elements (e.g., comb-2 SRS transmission) over a span of at
least 4 resource blocks in a symbol (a resource element in a symbol
may also be referred to as a subcarrier). However, a different
density may be needed to use the SRS to estimate a downlink channel
for precoding purposes. Aspects presented herein enable use of a
higher density of the resource elements in a slot to transmit the
SRS, which may lead to more accurate estimates of the downlink
channel and thus more accurate precoding of the downlink
transmissions from the TRP 604 to the UE 602, the UE 602 may
support transmitting the SRS on every resource element (e.g.,
comb-1 SRS transmission).
For example, to meet URLLC requirements in factory automation, the
CoMP may send small downlink packets that only occupy one resource
block. Thus, having a UE transmit the SRS over a span of a minimum
of four resource blocks may lead to a waste of wireless resource
and power consumption at the UE. To reduce resource consumption and
processing overhead, the UE 602 may support transmitting the SRS on
the resource elements in less than 4 resource blocks. In one
aspect, the UE 602 may support transmitting the SRS over a span of
an integer number of resource blocks in a slot with a granularity
of one resource block. In one aspect, the UE 602 may support
transmitting the SRS on every resource element over a span of less
than 4 resource blocks (e.g., 1, 2, or 3 resource blocks) in a
slot. Thus, the UE may transmit SRS that occupies every resource
element in a single resource block. Transmission of the SRS on
every resource element (e.g., each subcarrier in a symbol) in one
or more resource blocks in a slot may be referred to as a comb-1
SRS transmission.
The TRP 604 or the base station connected to the TRP 604 may
measure the SRS received from the UE 602 to estimate the downlink
channel for cluster management and scheduling. For example, the
base station connected to a group of TRPs may measure the SRS
received at a number of the TRPs to obtain link quality estimates
from the group of TRPs to the UE 602. The base station may use the
link quality estimates to identify a subset of the TRPs that may
cooperate to transmit to the UE 602. The resource elements required
to estimate the downlink channel for cluster management and
scheduling may not be as high as the resource elements required to
estimate the downlink channel for the precoding determination.
Nevertheless, the resource consumption required scales with the
density of the resource elements used for the SRS and the number of
UEs in the CoMP. A UE may be able to transmit the SRS down to a
minimum density of one of every 4 resource elements (e.g., comb-4
SRS transmission). However, this density may be beyond what is
needed for cluster management and scheduling. Thus, the
transmission of SRS with a density of one of every four resource
elements may cause an inefficient use of power and wireless
resources. In one aspect, to reduce the density of SRS transmission
further, the UE 602 may support transmitting the SRS on one of
every N resource elements (subcarriers) over a span of a number of
resource blocks in a slot, where N is greater than 4.
In one aspect, the UE 602 may measure a received CSI-RS transmitted
from the TRP 604 to estimate the downlink channel. The UE 602 may
transmit the link quality estimates of the downlink channel to the
TRP 604 for the TRP 604 or the base station connected to the TRP
604 to perform cluster management and scheduling. Similar to the
resource requirement for the SRS, the resource requirement for the
CSI-RS scales with the density of the resource elements used for
the CSI-RS transmissions and the number of UEs in the CoMP. CSI-RS
with a minimum density of one of every 24 resource elements over a
minimum of 24 resource blocks, may lead to an inefficient use of
wireless resources and power. Such a density may be more than
needed for cluster management/scheduling for CoMP. In one aspect,
to reduce the density of CSI-RS transmission by the TRP 604, the UE
602 may support receiving the CSI-RS on one of every N resource
elements over a span of a number of resource blocks in a slot,
where N is greater than 24. In one aspect, the UE 602 may support
receiving the CSI-RS over a span of less than 2 resource blocks in
a slot. In one aspect, the UE 602 may support receiving more than a
threshold number of CSI-RS resources from a number of TRPs
connected with the base station during a slot. In one aspect, the
threshold number of CSI-RS resources received in a slot includes a
threshold number of non-zero power (NZP) CSI-RS resources received
in a component carrier during a slot, where the threshold number of
NZP CSI-RS resources is greater than 32.
The TRP 604 may receive the information indicating the
configuration supported by the UE 602 for uplink SRS transmission
and for downlink CSI-RS reception. The TRP 604 or the base station
connected to the TRP 604 may generate, at 610, configuration
information for SRS transmission(s) from the UE 602 to the TRP 604
or configuration information for reception by the UE 602 of
CSI-RS(s) transmitted from the TRP 604 based on the supported
configuration of the UE 602. The supported configuration of the UE
602 may set the upper bounds of the configuration information
generated for the UE 602. For example, if the UE 602 supports
comb-1 SRS transmissions over a span of less than 4 resource blocks
in a slot, the TRP 604 or the base station connected to the TRP 604
may generate configuration information for the UE 602 to transmit
the SRS on every resource element over a span of 1 resource block
in a slot for the TRP 604 or the base station connected to the TRP
604, e.g., to enable the TRP to estimate the downlink channel for
downlink transmission precoding. In another example, if the UE 602
supports greater than comb-4 SRS transmissions over a number of
resource blocks in a slot, the TRP 604 or the base station
connected to the TRP 604 may generate configuration information for
the UE 602 to transmit the SRS on one of every 5 resource elements
over a span of two resource blocks in a slot for the TRP 604 or the
base station connected to the TRP 604, e.g., to enable the TRP to
estimate the downlink channel for cluster management and
scheduling.
In one aspect, the configuration information generated at 610 may
include a periodicity of the resource blocks, slots, subframes,
etc., used for the SRS transmissions. The configuration information
may include a sequence and a cyclic shift of the sequence used to
transmit the SRS. The configuration information may include a time
hopping sequence used to transmit the SRS. The configuration
information may include a comb-offset range. The configuration
information may include a position of the first resource element
and/or a position of the last resource element in addition to the
comb value. The resource elements used for the SRS transmission may
be configured to use a sequence and a cyclic shift of the sequence
in the time domain or a phase ramp in the frequency domain. In this
way, different UEs may use the same resource elements for the
transmissions of their respective SRS resources by using different
cyclic shifts of a sequence or using different sequences. In one
aspect, the set of cyclic shifts for a sequence that may be used
for the SRS transmissions may depend on the comb value of the SRS
resources (e.g., comb-2 or comb-4). In one aspect, the number of
cyclic shifts for a sequence may also depend on the number of
resource elements or subcarriers in a symbol used for the SRS
transmissions. For example, if 30 resource elements in a symbol are
used for the SRS transmissions, up to 30 cyclic shifts may be
configured. If 50 resource elements in a symbol are used for the
SRS transmission, up to 50 cyclic shifts may be configured. In one
aspect, the number of cyclic shifts for a sequence may depend on a
duration of the symbol and the delay spread of the uplink
channel.
In one aspect, if the UE 602 supports greater than comb-24 CSI-RS
receptions over a span of less than two resource blocks in a slot,
the TRP 604 or the base station connected to the TRP 604 may
generate configuration information for the UE 602 to receive CSI-RS
on one of every 25 resource elements over a span of 1 resource
blocks in a slot (e.g., use only 1 resource element in 1 resource
block in a slot) to estimate the downlink channel for cluster
management and scheduling. In one example, the TRP 604 or the base
station connected to the TRP 604 may generate configuration
information for the UE 602 to receive CSI-RS on one of every 24
resource elements as supported by the existing 5G standard but over
a span of less than 24 resource blocks. In one aspect, the
generated configuration information may include one of more of a
periodicity of the resource blocks, slots, subframes, etc., used
for the CSI-RS receptions, a time hopping sequence used to transmit
the CSI-RS by the TRP 604, the position of the first resource block
used for the CSI-RS receptions, the position of the first resource
element within the resource blocks used for the CSI-RS receptions,
etc., in addition to the density of the resource elements and the
number of resource blocks spanned by the resource elements used for
the CSI-RS receptions.
In 612, the TRP 604 may transmit to the UE 602 the generated
configuration information for one or more SRS transmissions from
the UE 602 to the TRP 604 or configuration information for one or
more receptions by the UE 602 of CSI-RS transmitted from the TRP
604. In one aspect, the TRP 604 may transmit the generated
configuration information in one or more of a radio resource
control (RRC) message, a medium access control (MAC) control
element (CE), a non-access stratum (NAS) message, or downlink
control information (DCI).
In 614, based on the configuration information received from the
TRP 604, the UE 602 may generate one or more SRS transmissions to
the TRP 604. Similarly, the UE may use the configuration
information to receive the CSI-RS transmitted from the TRP 604. In
one aspect, if the configuration information indicates the UE 602
may transmit the SRS on every resource element over a span of 1
resource block, the UE 602 may generate a first set of SRS on every
resource element of a resource block in a slot. In one aspect, the
UE 602 may generate a first set of SRS on every resource element
over a span of 2 resource blocks in a slot. The UE 602 may generate
the first set of comb-1 SRS transmissions or other dense SRS
transmissions over a span of one or more resource blocks in a slot
for the TRP 604 or the base station connected to the TRP 604 to
estimate the downlink channel for downlink transmission
precoding.
In one aspect, if the configuration information indicates the UE
602 may transmit the SRS on comb-5 SRS transmission or other comb-N
SRS transmissions greater than comb-4, the UE 602 may generate a
second set of SRS on one of every 5 resource elements or one of
every resource elements of values greater than 4 over a span of one
or more resource blocks in a slot for the TRP 604 or the base
station connected to the TRP 604 to estimate the downlink channel
for cluster management and scheduling. In one aspect, the UE 602
may generate a sequence and a cyclic shift of the sequence used to
transmit the second set of SRS based on the configuration
information. In one aspect, the UE 602 may generate a time hopping
sequence and may generate the second set of SRS using the time
hopping sequence based on the configuration information. The
density of the resource elements used for the first set of SRS may
be higher than the density of the resource elements used for the
second set of SRS. In other words, the comb value of the second set
of SRS may be greater than the comb value of the first set of
SRS.
In one aspect, if the configuration information indicates the UE
602 may receive CSI-RS on one of every N resource elements over a
span of one or more resource blocks where N is 25 or other values
greater than 24, the UE 602 may configure itself to receive the
CSI-RS on one of every 25 resource elements or one of every
resource elements of values greater than 24 over a span of one or
more resource blocks in a slot.
In 616, the UE 602 may transmit the generated first set of SRS to
the TRP 604. For example, the UE 602 may transmit a first set of
comb-1 SRS transmission over a span of one or more resource blocks
in a slot for the TRP 604 or the base station connected to the TRP
604 to estimate the downlink channel for downlink transmission
precoding. FIG. 7 illustrates an example of an SRS transmission
over each resource element of a resource block that may span one
resource block or two resource blocks.
In 618, the UE 602 may transmit the generated second set of SRS to
the TRP 604. The second set of SRS may have a different density
that the first set of SRS, and may be for different use by the TRP
or base station. For example, the UE 602 may transmit a second set
of comb-5 SRS transmission over a span of one or more resource
blocks in a slot for the TRP 604 or the base station connected to
the TRP 604 to estimate the downlink channel for cluster management
and scheduling. FIG. 8 illustrates an example of an SRS
transmission having an example density.
In 620, the UE 602 may receive a set of CSI-RS from the TRP 604
based on the configuration information received in 612. For
example, the UE 602 may receive a set of CSI-RS on one of every 25
resource elements over a span of one or more resource blocks in a
slot. The UE 602 may measure the CSI-RS resources and may transmit
the measured CSI-RS resources to the TRP 604 for the TRP 604 to
estimate the downlink channel for cluster management and
scheduling. FIG. 8 illustrates an example of an CSI-RS transmission
having an example density.
FIG. 7 illustrates a configuration 700 of using every resource
element or subcarrier over a span of two resource blocks in a slot
to transmit SRS resources from a UE to support precoding for
downlink transmissions in accordance with certain aspects of the
disclosure. In the comb-1 SRS transmissions of FIG. 7, all twelve
resource elements in the last symbol of each of the two resource
blocks are used to transmit the SRS.
FIG. 8 illustrates a configuration 800 of using one of every 36
resource elements or subcarriers over a number of resource blocks
in a slot to transmit SRS resources from a UE to support cluster
management and scheduling in accordance with certain aspects of the
disclosure. In the comb-36 transmissions of FIG. 8, the two
resource elements used to transmit the SRS are separated by 36
resource elements in the last symbol over a span of four resource
blocks in the slot. FIG. 8 may also illustrate a configuration of
using one of every 36 resource elements or subcarriers over a
number of resource blocks in a slot to receive CSI-RS resources
from a TRP to support cluster management and scheduling.
FIG. 9 is a flowchart 900 of a method of wireless communication
that may be implemented by a UE or a component of a UE (e.g., UE
104, 350, 504, 602; the apparatus 1000, 1000'; the processing
system 1114, which may include the memory 360 and which may be the
entire UE 350 or a component of the UE, such as the TX processor
368, the RX processor 356, and/or the controller/processor 359).
The method may be performed by the UE configured to support CoMP.
Optional aspects are illustrated with a dashed line. The method may
help the UE to transmit SRS and/or receive CSI-RS in a more
efficient manner that supports the unique needs of cluster
management and scheduling in CoMP and/or precoding for downlink
transmissions in CoMP.
At 902, the UE may transmit its supported configuration for uplink
SRS transmission and/or its supported configuration for downlink
CSI-RS reception for communication with a plurality of TRPs. The UE
may transmit the supported configuration information to one or more
TRPs. For example, support component 1004 and/or transmission
component 1002 of apparatus 1000 may transmit the supported
configuration. As use of a higher density of the resource elements
in a slot to transmit the SRS may lead to more accurate estimates
of the downlink channel and thus more accurate precoding of the
downlink transmissions from the TRPs to the UE, the UE may support
transmitting the SRS on every resource element (e.g., comb-1 SRS
transmission). In one aspect, the UE may support transmitting the
SRS over a span of an integer number of resource blocks in a slot
with a granularity of one resource block. In one aspect, the UE may
support transmitting the SRS on every resource element over a span
of less than 4 resource blocks (e.g., 1, 2, or 3 resource blocks)
in a slot. In one aspect, to reduce the density of SRS transmission
for cluster management and scheduling, the UE may support
transmitting the SRS on one of every N resource elements over a
span of a number of resource blocks in a slot, where N is greater
than 4.
In one aspect, to reduce the density of CSI-RS transmission by the
TRPs, the UE may support receiving the CSI-RS on one of every N
resource elements over a span of a number of resource blocks in a
slot, where N is greater than 24. In one aspect, the UE may support
receiving the CSI-RS over a span of less than 2 resource blocks in
a slot. In one aspect, the UE may support receiving more than a
threshold number of CSI-RS resources from a number of TRPs
connected with the base station during a slot. In one aspect, the
threshold number of CSI-RS resources received in a slot includes a
threshold number of non-zero power (NZP) CSI-RS resources received
in a component carrier during a slot, where the threshold number of
NZP CSI-RS resources is greater than 32.
At 904, the UE may receive, in response to transmitting the
supported configuration(s), configuration information for SRS
transmission(s) from the UE to the TRPs and/or configuration
information for reception by the UE of CSI-RS(s) from the TRPs
based on the supported configuration of the UE. For example,
configuration component 1008 and/or reception component 1006 of
apparatus 1000 may receive the configuration information. The
configuration information may be received from the TRPs in one or
more of an RRC message, a MAC CE, a NAS message, or a DCI. The
supported configuration of the UE may set the upper bounds of the
configuration information generated for the UE. In one aspect, if
the UE supports comb-1 SRS transmissions over a span of less than 4
resource blocks in a slot, the UE may receive configuration
information to transmit the SRS on every resource element over a
span of 1 resource block in a slot. In another example, if the UE
supports greater than comb-4 SRS transmissions over a number of
resource blocks in a slot, the UE may receive configuration
information to transmit the SRS on one of every 5 resource elements
over a span of two resource blocks in a slot. In one aspect, if the
UE supports greater than comb-24 CSI-RS receptions over a span of
less than two resource blocks in a slot, the UE may receive
configuration information for the UE to receive CSI-RS on one of
every 25 resource elements over a span of 1 resource blocks in a
slot from the TRPs.
At 906, the UE may communicate with at least a subset of the
plurality of TRPs using the SRS transmission(s) and/or the CSI-RS
reception on resource elements assigned based on the configuration
information. Based on the configuration information received from
the TRPs, the UE may generate one or more SRS transmissions to the
TRPs or may configure itself to receive the CSI-RS transmitted from
the TRPs. For example, the supported configuration may comprise an
SRS comb density supported by the UE, and the UE's communication
with at least a subset of the TRPs may include transmitting the SRS
transmission on resource elements assigned based on the comb
density supported by the UE. The SRS transmission may comprise a
cyclic shift based on a number of the resource elements assigned
for the SRS transmission. A number of cyclic shifts in a set of
cyclic shifts for a sequence for the SRS transmissions may be based
on a value of the comb density or a number of resource elements
assigned for the SRS transmission. In one aspect, if the
configuration information indicates that the UE may transmit the
SRS on every resource element over a span of 1 resource block, the
UE may generate a first set of SRS on every resource element of a
resource block in a slot. In one aspect, if the configuration
information indicates that the UE may transmit the SRS on comb-5
SRS transmission or other comb-N SRS transmissions greater than
comb-4, the UE may generate a second set of SRS on one of every 5
resource elements or one of every resource elements of values
greater than 4 over a span of one or more resource blocks in a
slot. In one aspect, if the configuration information indicates
that the UE may receive CSI-RS on one of every N resource elements
over a span of one or more resource blocks where N is 25 or other
values greater than 24, the UE may configure itself to receive the
CSI-RS on one of every 25 resource elements or one of every
resource elements of values greater than 24 over a span of one or
more resource blocks in a slot.
At 910, the UE may transmit a first set of SRS on one of every M
resource elements over an integer number of resource blocks in a
slot to the TRPs. For example, first set of SRS transmission
component 1010 and/or transmission component 1002 may transmit the
first set of SRS. For example, the UE may transmit a first set of
comb-1 SRS transmission over a span of one or more resource blocks
in a slot for the TRPs to estimate the downlink channel for
downlink transmission precoding.
At 912, the UE may transmit a second set of SRS on one of every J
resource elements over a number of resource blocks in a slot to the
TRPs. For example, second set of SRS transmission component 1012
and/or transmission component 1002 may transmit the second set of
SRS. J may be larger than M of 910 so that the density of SRS
resources for the second set of SRS may be less than the density of
SRS resources for the first set of SRS. For example, the UE may
transmit a second set of comb-5 SRS transmission over a span of one
or more resource blocks in a slot for the TRPs to estimate the
downlink channel for cluster management and scheduling.
At 914, the UE may receive a set of CSI-RS on one of every N
resource elements over a number of resource blocks in a slot from
the TRPs, where N is greater than 24. For example, CSI-RS component
1014 and/or reception component 1006 may receive the CSI-RS based
on the configuration information received from the base station.
For example, the UE may receive a set of CSI-RS on one of every 25
resource elements over a span of one or more resource blocks in a
slot from the TRPs. The UE may measure the CSI-RS resources and may
transmit the measured CSI-RS resources to the TRPs for the TRPs to
estimate the downlink channel for cluster management and
scheduling. In another example, the UE may receive the CSI-RS over
a span of K resource blocks during a slot, wherein K is less than
2. The UE may receive the CSI-RS on one of every M resource
elements over a span of J resource blocks during a slot, wherein M
is greater than or equal to N. Communicating with the subset of the
plurality of TRPs may comprise receiving, from one of the plurality
of TRPs, the CSI-RS on one of every said M resource elements over
the span of J resource blocks during a first slot.
FIG. 10 is a conceptual data flow diagram illustrating the data
flow between different modules/means/components in an exemplary
apparatus 1000 of a UE in accordance with certain aspects of the
disclosure. The apparatus 1000 may be the UE of 104, 350, 504, 602,
or the apparatus 1000' to support CoMP. The apparatus 1000 may
include a transmission component 1002, a support component 1004, a
reception component 1006, a configuration component 1008, a first
set of SRS transmission component 1010, a second set of SRS
transmission component 1012, and a CSI-RS component 1014.
The support component 1004 may be configured to generate the
apparatus's supported configuration for uplink SRS transmission and
its supported configuration for downlink CSI-RS reception to one or
more TRPs. The supported configuration may include transmitting the
SRS on every resource element (e.g., comb-1 SRS transmission),
transmitting the SRS over a span of an integer number of resource
blocks in a slot with a granularity of one resource block,
transmitting the SRS on every resource element over a span of less
than 4 resource blocks (e.g., 1, 2, or 3 resource blocks) in a
slot, transmitting the SRS on one of every N resource elements over
a span of a number of resource blocks in a slot, where N is greater
than 4, etc. The supported configuration may include receiving the
CSI-RS on one of every N resource elements over a span of a number
of resource blocks in a slot, where N is greater than 24, receiving
the CSI-RS over a span of K resource blocks in a slot, where K is
less than 2, etc.
The transmission component 1002 may be configured to transmit the
supported configuration of the SRS and CSI-RS generated by the
supported configuration of SRS and CSI-RS component 1014 to the
base station 1050. The base station 1050 may correspond to, e.g.,
the base station 102, 180, 310, 604, 1300, or the apparatus
1300'.
The configuration component 1008 may be configured to receive the
configuration information for one or more SRS transmissions from
the apparatus 1000 to the base station 1050 or configuration
information for one or more receptions by the apparatus 1000 of
CSI-RS transmitted from the base station 1050 based on the
supported configuration of the UE. The configuration information
may be received through the reception component 1006. The supported
configuration of the UE may set the upper bounds of the
configuration information generated for the UE. The configuration
information may indicate to the apparatus 1000 to transmit the SRS
on every resource element over a span of 1 resource block in a
slot. In another aspect, the configuration information may indicate
to the apparatus 1000 to transmit the SRS on one of every 5
resource elements over a span of two resource blocks in a slot. In
one aspect, the configuration information may indicate to the
apparatus 1000 to receive CSI-RS on one of every 25 resource
elements over a span of 1 resource blocks in a slot from the base
station 1050.
The configuration information may be used by the first set of SRS
transmission component 1010 to generate a first set of SRS
transmission. In one aspect, first set of SRS transmission
component 1010 may be configured to generate a first set of SRS on
every resource element of a resource block in a slot.
The configuration information may be used by the second set of SRS
transmission component 1012 to generate the second set of SRS
transmission. In one aspect, the second set of SRS transmission
component 1012 may be configured to generate a second set of SRS
one of every 5 resource elements or one of every resource elements
of values greater than 4 over a span of one or more resource blocks
in a slot. The first set of SRS transmission and the second set of
SRS transmission may be sent to the transmission component for
transmission to the base station 1050.
The configuration information may be used by the CSI-RS component
1014 to receive the set of CSI-RS resources received from the base
station 1050 through the reception component 1006. The CSI-RS
component 1014 may be configured to receive the CSI-RS on one of
every 25 resource elements or one of every resource elements of
values greater than 24 over a span of one or more resource blocks
in a slot.
FIG. 11 is a diagram illustrating an example of a hardware
implementation for an apparatus 1000' of a UE employing a
processing system 1114 in accordance with certain aspects of the
disclosure. The processing system 1114 may be implemented with a
bus architecture, represented generally by the bus 1108. The bus
1108 may include any number of interconnecting buses and bridges
depending on the specific application of the processing system 1114
and the overall design constraints. The bus 1108 links together
various circuits including one or more processors and/or hardware
components, represented by the processor 1104, the components 1010,
1012, 1014, 1016, 1018, and the computer-readable medium/memory
1106. The bus 1108 may also link various other circuits such as
timing sources, peripherals, voltage regulators, and power
management circuits, which are well known in the art, and
therefore, will not be described any further.
The processing system 1114 may be coupled to a transceiver 1110.
The transceiver 1110 is coupled to one or more antennas 1120. The
transceiver 1110 provides a means for communicating with various
other apparatus over a transmission medium. The transceiver 1110
receives a signal from the one or more antennas 1120, extracts
information such as the configuration information of the SRS and
CSI-RS, or the CSI-RS from the received signal transmitted by the
base station, and provides the extracted information to the
processing system 1114, specifically the reception component 1006,
the configuration information of SRS and configuration component
1008, and the CSI-RS component 1014. In addition, the transceiver
1110 receives information from the processing system 114,
specifically the supported configuration of SRS and CSI-RS, the
first set of SRS transmission, or the second set of SRS
transmission, and based on the received information, generates a
signal to be applied to the one or more antennas 1120. The
processing system 1114 includes a processor 1104 coupled to a
computer-readable medium/memory 1106. The processor 1104 is
responsible for general processing, including the execution of
software stored on the computer-readable medium/memory 1106. The
software, when executed by the processor 1104, causes the
processing system 1114 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 1106 may also be used for storing data that is
manipulated by the processor 1104 when executing software. The
processing system further includes at least one of the components
1002, 1004, 1006, 1008, 1010, 1012, and 1014. The components may be
software components running in the processor 1104 configured to
perform the stated processes/algorithm, resident/stored in the
computer readable medium/memory 1106 for implementation by the
processor 1104, one or more hardware components specifically
configured to carry out the stated processes/algorithm, one or more
hardware components coupled to the processor 1104, or some
combination thereof. Alternatively, the processing system 1114 may
be the entire UE (e.g., see 350 of FIG. 3).
In one configuration, the apparatus 1000' may include means for
generating the supported configuration of SRS and CSI-RS by the
apparatus 1000'. The means for generating the supported
configuration of SRS and CSI-RS may be implemented by the supported
configuration of SRS and CSI-RS component 1014. The apparatus 1000'
may include means for receiving the configuration information of
SRS and CSI-RS from a base station. The means for receiving the
configuration information of SRS and CSI-RS from a base station may
be implemented by the configuration information of SRS and CSI-RS
component 1014. The apparatus 1000' may include means for
generating the first set of SRS and means for generating the second
set of SRS based on the configuration information for the SRS. The
means for generating the first set of SRS may be implemented by the
first set of SRS transmission component 1010. The means for
generating the second set of SRS may be implemented by the second
set of SRS transmission component 1012. The apparatus 1000' may
include means for receiving CSI-RS from the base station based on
the configuration information for the CSI-RS. The means for
receiving the CSI-RS from the base station may be implemented by
the CSI-RS component 1014.
FIG. 12 is a flowchart 1200 of a method of wireless communication
that may be implemented by a base station in accordance with
certain aspects of the disclosure. The method may be performed by
the TRP or base station or a component of a base station (e.g.,
base station 102, 180, 310, 604, apparatus 1300, 1300' the
processing system 1414, which may include the memory 376 and which
may be the entire base station 310 or a component of the base
station 310, such as the TX processor 316, the RX processor 370,
and/or the controller/processor 375). Optional aspects are
illustrated with a dashed line. The method may help the base
station/TRP to receive SRS and/or transmit CSI-RS in a more
efficient manner that supports the unique needs of cluster
management and scheduling in CoMP and/or precoding for downlink
transmissions in CoMP.
At 1202, the base station may receive, e.g., via one or more TRPs
connected to the base station, a supported configuration for uplink
SRS transmission and/or the supported configuration for downlink
CSI-RS reception by a UE. The reception may be performed by support
component 1306 and/or reception component 1304 in apparatus 1300.
In one aspect, the base station may receive an indication that UE
supports transmitting the SRS on every resource element (e.g.,
comb-1 SRS transmission). In one aspect, the base station may
receive an indication that the UE supports transmitting the SRS
over a span of an integer number of resource blocks in a slot with
a granularity of one resource block. In one aspect, the base
station may receive an indication that the UE supports transmitting
the SRS on every resource element over a span of less than 4
resource blocks (e.g., 1, 2, or 3 resource blocks) in a slot. In
one aspect, to reduce the density of SRS transmission for cluster
management and scheduling, the base station may receive an
indication that the UE supports transmitting the SRS on one of
every N resource elements over a span of a number of resource
blocks in a slot, where N is greater than 4.
In one aspect, to reduce the density of CSI-RS transmission by the
TRPs, the base station may receive an indication that the UE
supports receiving the CSI-RS on one of every N resource elements
over a span of a number of resource blocks in a slot, where N is
greater than 24. In one aspect, the base station may receive an
indication that the UE supports receiving the CSI-RS over a span of
less than 2 resource blocks in a slot. In one aspect, the base
station may receive an indication that the UE supports receiving
more than a threshold number of CSI-RS resources from a number of
TRPs connected with the base station during a slot. In one aspect,
the threshold number of CSI-RS resources received in a slot
includes a threshold number of non-zero power (NZP) CSI-RS
resources received in a component carrier during a slot, where the
threshold number of NZP CSI-RS resources is greater than 32.
At 1204, the base station may generate configuration information
for one or more SRS transmissions from the UE to the base station
or configuration information for one or more receptions by the UE
of CSI-RS transmitted from the base station based on the supported
configuration of the UE. For example, configuration component 1308
of apparatus 1300 may generate the configuration information. The
supported configuration of the UE may set the upper bounds of the
configuration information generated for the UE. In one aspect, the
configuration information may indicate to the UE to transmit the
SRS on every resource element over a span of 1 resource block in a
slot. In another example, the configuration information may
indicate to the UE to transmit the SRS on one of every 5 resource
elements over a span of two resource blocks in a slot. In one
aspect, the configuration information may indicate to the UE to
receive CSI-RS on one of every 25 resource elements over a span of
1 resource blocks in a slot from the TRPs.
At 1206, the base station may transmit through the TRPs the
generated configuration information to the UE. For example, the
transmission component 1310 may transmit the configuration
information. The subset of the TRPs that receive the supported
configuration for the SRS transmission and the supported
configuration for the CSI-RS reception by the UE may be different
from the subset of the TRPs that transmit the generated
configuration information to the UE.
At 1208, the base station may communicate with the UE by receiving
the SRS or transmitting the CSI-RS on resource elements assigned
based on the configuration information through a subset of the
TRPs. The subset of TRPs receiving the SRS or transmitting the
CSI-RS may be different from the subset of the TRPs that receive
the supported configuration for the SRS transmission and the
supported configuration for the CSI-RS reception from the UE, or
the subset of the TRPs that transmit the generated configuration
information to the UE.
The supported configuration may comprise an SRS comb density
supported by the UE, and communicating with at least the subset of
the plurality of TRPs may include receiving the SRS transmission on
resource elements assigned by the base station based on the comb
density supported by the UE. The SRS may comprise a cyclic shift
based on a number of the resource elements assigned for the SRS
transmission, and a number of cyclic shifts in a set of cyclic
shifts for a sequence for the SRS may be based on a value of the
comb density for the SRS or a number of resource elements assigned
for the SRS.
Based on the configuration information, the base station may
receive one or more SRS transmissions from the UE or may transmit
the CSI-RS to the UE. In one aspect, if the configuration
information indicates that the UE may transmit the SRS on every
resource element over a span of 1 resource block, the base station
may receive a first set of SRS on every resource element of a
resource block in a slot. In one aspect, if the configuration
information indicates that the UE may transmit the SRS on comb-5
SRS transmission or other comb-N SRS transmissions greater than
comb-4, the base station may receive a second set of SRS on one of
every 5 resource elements or one of every resource elements of
values greater than 4 over a span of one or more resource blocks in
a slot. In one aspect, if the configuration information indicates
that the UE may receive CSI-RS on one of every N resource elements
over a span of one or more resource blocks where N is 25 or other
values greater than 24, the base station may transmit the CSI-RS on
one of every 25 resource elements or one of every resource elements
of values greater than 24 over a span of one or more resource
blocks in a slot.
At 1210, the base station may receive a first set of SRS on one of
every M resource elements over an integer number of resource blocks
in a slot. For example, first SRS component 1312 of apparatus 1300
may receive the first set of SRS. For example, the base station may
receive a first set of comb-1 SRS transmission over a span of one
or more resource blocks in a slot for the base station to estimate
the downlink channel for downlink transmission precoding.
At 1212, the base station may receive a second set of SRS on one of
every J resource elements over a number of resource blocks in a
slot. For example, second SRS component 1314 of apparatus 1300 may
receive the second set of SRS. J may be larger than M of 910 so
that the density of SRS resources for the second set of SRS may be
less than the density of SRS resources for the first set of SRS.
For example, the base station may receive a second set of comb-5
SRS transmission over a span of one or more resource blocks in a
slot for the base station to estimate the downlink channel for
cluster management and scheduling.
At 1214, the base station may transmit a set of CSI-RS on one of
every N resource elements over a number of resource blocks in a
slot, where N is greater than 24. For example, first CSI-RS
component 1316 of apparatus 1300 may transmit the CSI-RS. For
example, the base station may transmit a set of CSI-RS on one of
every 25 resource elements over a span of one or more resource
blocks in a slot. The UE may measure the CSI-RS resources and may
transmit the measured CSI-RS resources to the base station for the
base station to estimate the downlink channel for cluster
management and scheduling.
FIG. 13 is a conceptual data flow diagram illustrating the data
flow between different modules/means/components in an exemplary
apparatus 1300 that may comprise a base station or a component of a
base station in accordance with certain aspects of the disclosure.
The apparatus 1300 may be the base station of 102, 180, 310, 604,
1050. The apparatus 1300 may include a reception component 1304, a
support component 1306, a configuration component 1308, a
transmission component 1310, a first SRS component 1312, a second
SRS component 1314, a CSI-RS component 1316, and a downlink channel
and link quality estimation component 1318.
The support component 1306 may be configured to receive the
apparatus's supported configuration for uplink SRS transmission and
its supported configuration for downlink CSI-RS reception through
the reception component 1304 from the UE 1350. The supported
configuration may include transmitting the SRS on every resource
element (e.g., comb-1 SRS transmission), transmitting the SRS over
a span of an integer number of resource blocks in a slot with a
granularity of one resource block, transmitting the SRS on every
resource element over a span of less than 4 resource blocks (e.g.,
1, 2, or 3 resource blocks) in a slot, transmitting the SRS on one
of every N resource elements over a span of a number of resource
blocks in a slot, where N is greater than 4, etc.
The configuration component 1308 may be configured to generate the
configuration information for one or more SRS transmissions from UE
to the apparatus 1300 or configuration information for one or more
transmissions of CSI-RS from the base station to the UE 1350 based
on the supported configuration of the UE 1350. The configuration
information may be transmitted through the transmission component
1310. The supported configuration of the UE may set the upper
bounds of the configuration information generated for the UE. The
configuration information may indicate to the UE 1350 to transmit
the SRS on every resource element over a span of 1 resource block
in a slot. In another aspect, the configuration information may
indicate to the UE 1350 to transmit the SRS on one of every 5
resource elements over a span of two resource blocks in a slot. In
one aspect, the configuration information may indicate to the UE
1350 to receive CSI-RS on one of every 25 resource elements over a
span of 1 resource blocks in a slot from the base station 1050.
The configuration information may be used by the first SRS
component 1312 to receive a first set of SRS transmission from the
UE 1350. In one aspect, first SRS component 1312 may be configured
to receive a first set of SRS on every resource element of a
resource block in a slot.
The configuration information may be used by the second SRS
component 1314 to receive the second set of SRS transmission from
the UE 1350. In one aspect, the second SRS component 1314 may be
configured to receive a second set of SRS one of every 5 resource
elements or one of every resource elements of values greater than 4
over a span of one or more resource blocks in a slot. The first set
of SRS transmission and the second set of SRS transmission may be
received from the reception component 1304.
The configuration information may be used by the CSI-RS component
1316 to transmit the set of CSI-RS resources to the UE 1350 through
the transmission component 1310. The CSI-RS component 1316 may be
configured to transmit the CSI-RS on one of every 25 resource
elements or one of every resource elements of values greater than
24 over a span of one or more resource blocks in a slot.
The downlink channel and link quality estimation component 1318 may
be configured to estimate one or more downlink channels with the UE
1350 based on the first set of SRS to determine precoding for
downlink transmission. The downlink channel and link quality
estimation component 1318 may also be configured to estimate a link
quality of one or more uplink channels or one or more downlink
channels with the UE 1350 based on one or more of the first set of
SRS, the second set of SRS, or measurements of the CSI-RS by the UE
1350 transmitted from the UE 1350 to the base station, e.g.,
apparatus 1300.
FIG. 14 is a diagram illustrating an example of a hardware
implementation for an apparatus 1300' of a base station employing a
processing system 1414 in accordance with certain aspects of the
disclosure. The processing system 1414 may be implemented with a
bus architecture, represented generally by the bus 1408. The bus
1408 may include any number of interconnecting buses and bridges
depending on the specific application of the processing system 1414
and the overall design constraints. The bus 1408 links together
various circuits including one or more processors and/or hardware
components, represented by the processor 1404, the components 1410,
1412, 1414, 1416, 1418, and the computer-readable medium/memory
1406. The bus 1408 may also link various other circuits such as
timing sources, peripherals, voltage regulators, and power
management circuits, which are well known in the art, and
therefore, will not be described any further.
The processing system 1414 may be coupled to a transceiver 1410.
The transceiver 1410 is coupled to one or more antennas 1420. The
transceiver 1410 provides a means for communicating with various
other apparatus over a transmission medium. The transceiver 1410
receives a signal from the one or more antennas 1120, extracts
information such as the supported configuration information of the
SRS and CSI-RS, or the SRS from the received signal transmitted by
the UE and provides the extracted information to the processing
system 1114, specifically the reception component 1304, the
supported configuration of SRS and CSI-RS by support component
1306, the first set of SRS component 1312, and the second SRS
component 1314. In addition, the transceiver 1110 receives
information from the processing system 114, specifically the
configuration information of SRS and CSI-RS, the CSI-RS
transmission, and based on the received information, generates a
signal to be applied to the one or more antennas 1420. The
processing system 1414 includes a processor 1404 coupled to a
computer-readable medium/memory 1406. The processor 1404 is
responsible for general processing, including the execution of
software stored on the computer-readable medium/memory 1406. The
software, when executed by the processor 1404, causes the
processing system 1414 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 1406 may also be used for storing data that is
manipulated by the processor 1404 when executing software. The
processing system further includes at least one of the components
1404, 1406, 1408, 1410, 1412, 1414, 1416, and 1418. The components
may be software components running in the processor 1104 configured
to perform the stated processes/algorithm, resident/stored in the
computer readable medium/memory 1406 for implementation by the
processor 1404, one or more hardware components specifically
configured to carry out the stated processes/algorithm, one or more
hardware components coupled to the processor 1404, or some
combination thereof. Alternatively, the processing system 1414 may
be the entire base station (e.g., see 310 of FIG. 3).
In one configuration, the apparatus 1300' may include means for
receiving the supported configuration of SRS and CSI-RS by the UE.
The means for receiving the supported configuration of SRS and
CSI-RS by the UE may be implemented by the configuration
information of SRS and CSI-RS by support component 1306. The
apparatus 1300' may include means for generating the configuration
information of SRS and CSI-RS. The means for generating the
configuration information of SRS and CSI-RS may be implemented by
the configuration information of SRS and CSI-RS for configuration
component 1308. The apparatus 1300' may include means for receiving
the first set of SRS and means for receiving the second set of SRS
based on the configuration information for the SRS. The means for
receiving the first set of SRS may be implemented by the first SRS
component 1312. The means for receiving the second set of SRS may
be implemented by the second SRS component 1314. The apparatus
1300' may include means for transmitting CSI-RS based on the
configuration information for the CSI-RS. The means for
transmitting the CSI-RS from the base station may be implemented by
the CSI-RS component 1314. The apparatus 1300' may include means
for estimating one or more downlink channels using the first set of
SRS or means for estimating a link quality of one or more uplink
channels or one or more downlink channels based on one or more of
the first set of SRS, the second set of SRS, or measurements of the
CSI-RS received by the apparatus 1300'. The means for estimating
the downlink channels or means for estimating a link quality of the
uplink or downlink channels may be implemented by the downlink
channel and link quality estimation component 1318.
It is understood that the specific order or hierarchy of blocks in
the processes/flowcharts disclosed is an illustration of exemplary
approaches. Based upon design preferences, it is understood that
the specific order or hierarchy of blocks in the
processes/flowcharts may be rearranged. Further, some blocks may be
combined or omitted. The accompanying method claims present
elements of the various blocks in a sample order, and are not meant
to be limited to the specific order or hierarchy presented.
The previous description is provided to enable any person skilled
in the art to practice the various aspects described herein.
Various modifications to these aspects will be readily apparent to
those skilled in the art, and the generic principles defined herein
may be applied to other aspects. Thus, the claims are not intended
to be limited to the aspects shown herein, but is to be accorded
the full scope consistent with the language claims, wherein
reference to an element in the singular is not intended to mean
"one and only one" unless specifically so stated, but rather "one
or more." The word "exemplary" is used herein to mean "serving as
an example, instance, or illustration." Any aspect described herein
as "exemplary" is not necessarily to be construed as preferred or
advantageous over other aspects. Unless specifically stated
otherwise, the term "some" refers to one or more. Combinations such
as "at least one of A, B, or C," "one or more of A, B, or C," "at
least one of A, B, and C," "one or more of A, B, and C," and "A, B,
C, or any combination thereof" include any combination of A, B,
and/or C, and may include multiples of A, multiples of B, or
multiples of C. Specifically, combinations such as "at least one of
A, B, or C," "one or more of A, B, or C," "at least one of A, B,
and C," "one or more of A, B, and C," and "A, B, C, or any
combination thereof" may be A only, B only, C only, A and B, A and
C, B and C, or A and B and C, where any such combinations may
contain one or more member or members of A, B, or C. All structural
and functional equivalents to the elements of the various aspects
described throughout this disclosure that are known or later come
to be known to those of ordinary skill in the art are expressly
incorporated herein by reference and are intended to be encompassed
by the claims. Moreover, nothing disclosed herein is intended to be
dedicated to the public regardless of whether such disclosure is
explicitly recited in the claims. The words "module," "mechanism,"
"element," "device," and the like may not be a substitute for the
word "means." As such, no claim element is to be construed as a
means plus function unless the element is expressly recited using
the phrase "means for."
* * * * *
References